diff --git a/xwords4/common/comms.c b/xwords4/common/comms.c
index af3cdc963..108f425ad 100644
--- a/xwords4/common/comms.c
+++ b/xwords4/common/comms.c
@@ -34,6 +34,7 @@
 #include "dbgutil.h"
 #include "knownplyr.h"
 #include "device.h"
+#include "nli.h"
 
 #define HEARTBEAT_NONE 0
 
@@ -48,6 +49,10 @@
 #define NO_MSGID_BIT 0x0020
 #define HEADER_LEN_OFFSET 9
 
+/* Low two bits treated as channel, third as short-term flag indicating
+ * sender's role; rest can be random to aid detection of duplicate packets. */
+#define CHANNEL_MASK 0x0003
+
 #ifndef XWFEATURE_STANDALONE_ONLY
 
 #ifndef INITIAL_CLIENT_VERS
@@ -67,8 +72,8 @@ EXTERN_C_START
 
 typedef struct MsgQueueElem {
     struct MsgQueueElem* next;
-    XP_U8* msg;
-    XP_U16 len;
+    XP_U8* msg;                 /* ptr to NetLaunchInfo if isInvite is true */
+    XP_U16 len;                 /* stored as 0 if msg is a nli */
     XP_PlayerAddr channelNo;
 #ifdef DEBUG
     XP_U16 sendCount;           /* how many times sent? */
@@ -202,8 +207,7 @@ typedef enum {
  *                               prototypes 
  ****************************************************************************/
 static AddressRecord* rememberChannelAddress( CommsCtxt* comms, XWEnv xwe,
-                                              XP_PlayerAddr channelNo, 
-                                              XWHostID id,
+                                              XP_PlayerAddr channelNo, XWHostID id,
                                               const CommsAddrRec* addr, XP_U16 flags );
 static void augmentChannelAddr( CommsCtxt* comms, AddressRecord* rec,
                                 const CommsAddrRec* addr, XWHostID hostID );
@@ -217,7 +221,7 @@ static AddressRecord* getRecordFor( CommsCtxt* comms, XWEnv xwe,
 static void augmentSelfAddr( CommsCtxt* comms, XWEnv xwe, const CommsAddrRec* addr );
 static XP_S16 sendMsg( CommsCtxt* comms, XWEnv xwe, MsgQueueElem* elem,
                        CommsConnType filter );
-static MsgQueueElem* addToQueue( CommsCtxt* comms, XWEnv xwe, MsgQueueElem* newMsgElem );
+static MsgQueueElem* addToQueue( CommsCtxt* comms, XWEnv xwe, MsgQueueElem* newElem );
 static XP_Bool elems_same( const MsgQueueElem* e1, const MsgQueueElem* e2 ) ;
 static void freeElem( const CommsCtxt* comms, MsgQueueElem* elem );
 
@@ -228,7 +232,8 @@ static void sendConnect( CommsCtxt* comms, XWEnv xwe
 #endif
                          );
 static void notifyQueueChanged( const CommsCtxt* comms, XWEnv xwe );
-static XP_U16 makeFlags( const CommsCtxt* comms, XP_U16 headerLen, MsgID msgID );
+static XP_U16 makeFlags( const CommsCtxt* comms, XP_U16 headerLen,
+                         MsgID msgID );
 
 static XP_Bool formatRelayID( const CommsCtxt* comms, XWHostID hostID,
                               XP_UCHAR* buf, XP_U16* lenp );
@@ -872,10 +877,27 @@ comms_makeFromStream( MPFORMAL XWEnv xwe, XWStreamCtxt* stream,
 #ifdef DEBUG
         msg->sendCount = 0;
 #endif
-        msg->msg = (XP_U8*)XP_MALLOC( mpool, msg->len );
-        stream_getBytes( stream, msg->msg, msg->len );
+        XP_U16 len = msg->len;
+        if ( 0 == len ) {
+            XP_U32 nliLen = stream_getU32VL( stream );
+            XWStreamCtxt* nliStream = mem_stream_make_raw( MPPARM(comms->mpool)
+                                                           dutil_getVTManager(comms->dutil));
+            stream_getFromStream( nliStream, stream, nliLen );
+            NetLaunchInfo nli;
+            if ( nli_makeFromStream( &nli, nliStream ) ) {
+                msg->msg = (XP_U8*)XP_MALLOC( mpool, sizeof(nli) );
+                XP_MEMCPY( msg->msg, &nli, sizeof(nli) );
+                len = sizeof(nli); /* needed for checksum calc */
+            } else {
+                XP_ASSERT(0);
+            }
+            stream_destroy( nliStream, xwe );
+        } else {
+            msg->msg = (XP_U8*)XP_MALLOC( mpool, len );
+            stream_getBytes( stream, msg->msg, len );
+        }
 #ifdef COMMS_CHECKSUM
-        msg->checksum = dutil_md5sum( comms->dutil, xwe, msg->msg, msg->len );
+        msg->checksum = dutil_md5sum( comms->dutil, xwe, msg->msg, len );
 #endif
         msg->next = (MsgQueueElem*)NULL;
         *prevsQueueNext = comms->msgQueueTail = msg;
@@ -1110,7 +1132,18 @@ comms_writeToStream( CommsCtxt* comms, XWEnv XP_UNUSED_DBG(xwe),
 
         stream_putU32VL( stream, msg->len );
         stream_putU32( stream, msg->createdStamp );
-        stream_putBytes( stream, msg->msg, msg->len );
+        if ( 0 == msg->len ) {
+            XWStreamCtxt* nliStream = mem_stream_make_raw( MPPARM(comms->mpool)
+                                                           dutil_getVTManager(comms->dutil));
+            NetLaunchInfo* nli = (NetLaunchInfo*)msg->msg;
+            nli_saveToStream( nli, nliStream );
+            XP_U16 nliLen = stream_getSize( nliStream );
+            stream_putU32VL( stream, nliLen );
+            stream_getFromStream( stream, nliStream, nliLen );
+            stream_destroy( nliStream, xwe );
+        } else {
+            stream_putBytes( stream, msg->msg, msg->len );
+        }
     }
 
     /* This writes 2 bytes instead of 1 if it were smarter. Not worth the work
@@ -1336,6 +1369,18 @@ comms_getIsServer( const CommsCtxt* comms )
     return comms->isServer;
 }
 
+static MsgQueueElem*
+makeNewElem( const CommsCtxt* comms, XWEnv xwe, MsgID msgID,
+             XP_PlayerAddr channelNo )
+{
+    MsgQueueElem* newElem = (MsgQueueElem*)XP_CALLOC( comms->mpool,
+                                                      sizeof( *newElem ) );
+    newElem->createdStamp = dutil_getCurSeconds( comms->dutil, xwe );
+    newElem->channelNo = channelNo;
+    newElem->msgID = msgID;
+    return newElem;
+}
+
 static MsgQueueElem*
 makeElemWithID( CommsCtxt* comms, XWEnv xwe, MsgID msgID, AddressRecord* rec,
                 XP_PlayerAddr channelNo, XWStreamCtxt* stream )
@@ -1344,11 +1389,7 @@ makeElemWithID( CommsCtxt* comms, XWEnv xwe, MsgID msgID, AddressRecord* rec,
     XP_LOGFF( TAGFMT(%s), TAGPRMS, cbuf );
     XP_U16 streamSize = NULL == stream? 0 : stream_getSize( stream );
     MsgID lastMsgSaved = (!!rec)? rec->lastMsgSaved : 0;
-    MsgQueueElem* newMsgElem = (MsgQueueElem*)XP_CALLOC( comms->mpool,
-                                                         sizeof( *newMsgElem ) );
-    newMsgElem->channelNo = channelNo;
-    newMsgElem->msgID = msgID;
-    newMsgElem->createdStamp = dutil_getCurSeconds( comms->dutil, xwe );
+    MsgQueueElem* newElem = makeNewElem( comms, xwe, msgID, channelNo );
 
     XP_Bool useSmallHeader = !!rec && (COMMS_VERSION == rec->flags);
     XWStreamCtxt* hdrStream = mem_stream_make_raw( MPPARM(comms->mpool)
@@ -1400,18 +1441,38 @@ makeElemWithID( CommsCtxt* comms, XWEnv xwe, MsgID msgID, AddressRecord* rec,
         stream_getFromStream( msgStream, stream, streamSize );
     }
 
-    newMsgElem->len = stream_getSize( msgStream );
-    newMsgElem->msg = (XP_U8*)XP_MALLOC( comms->mpool, newMsgElem->len );
-    stream_getBytes( msgStream, newMsgElem->msg, newMsgElem->len );
+    newElem->len = stream_getSize( msgStream );
+    XP_ASSERT( 0 < newElem->len );
+    newElem->msg = (XP_U8*)XP_MALLOC( comms->mpool, newElem->len );
+    stream_getBytes( msgStream, newElem->msg, newElem->len );
     stream_destroy( msgStream, xwe );
 
 #ifdef COMMS_CHECKSUM
-    newMsgElem->checksum = dutil_md5sum( comms->dutil, xwe, newMsgElem->msg,
-                                         newMsgElem->len );
+    newElem->checksum = dutil_md5sum( comms->dutil, xwe, newElem->msg,
+                                      newElem->len );
 #endif
-    return newMsgElem;
+    XP_ASSERT( 0 < newElem->len ); /* else NLI assumptions fail */
+    return newElem;
 } /* makeElemWithID */
 
+#ifdef XWFEATURE_COMMS_INVITE
+static MsgQueueElem*
+makeInviteElem( CommsCtxt* comms, XWEnv xwe,
+                XP_PlayerAddr channelNo, const NetLaunchInfo* nli )
+{
+    MsgQueueElem* newElem = makeNewElem( comms, xwe, 0, channelNo );
+
+    XP_ASSERT( 0 == newElem->len );           /* len == 0 signals is NLI */
+    newElem->msg = XP_MALLOC( comms->mpool, sizeof(*nli) );
+    XP_MEMCPY( newElem->msg, nli, sizeof(*nli) );
+# ifdef COMMS_CHECKSUM
+    newElem->checksum = dutil_md5sum( comms->dutil, xwe, newElem->msg,
+                                      sizeof(*nli) );
+# endif
+    return newElem;
+}
+#endif
+
 XP_U16
 comms_getChannelSeed( CommsCtxt* comms )
 {
@@ -1426,6 +1487,78 @@ comms_getChannelSeed( CommsCtxt* comms )
     return result;
 }
 
+#ifdef XWFEATURE_COMMS_INVITE
+/* PENDING: this needs to handle more than MQTT!!!! */
+static XP_Bool
+isSameAddr( const CommsAddrRec* rec1, const CommsAddrRec* rec2 )
+{
+    XP_Bool result =
+        addr_hasType( rec1, COMMS_CONN_MQTT )
+        && addr_hasType( rec2, COMMS_CONN_MQTT )
+        && rec1->u.mqtt.devID == rec2->u.mqtt.devID;
+    LOG_RETURNF( "%s", boolToStr(result) );
+    return result;
+}
+
+/* We're adding invites to comms so they'll be persisted and resent etc. can
+   work in common code. Rule will be there's only one invitation present per
+   channel (remote device.) We'll add a channel if necessary. Then if there is
+   an invitation already there we'll replace it.
+
+   Interesting case is where I send two invitations only one of which can be
+   accepted (as e.g. when I invite one friend, then on not receiving a
+   response decide to invite a different friend instead. In the two-player
+   game case I can detect that there are too many invitations and delete/reuse
+   the previous channel when the new invitation is received. But what about
+   the two-remotes game? Would I delete the oldest that hadn't been responded
+   to? Or maybe keep them all, and when an invitation is responded to, meaning
+   that there's incoming traffic on that channel, I promote it somehow, and
+   when a game is complete (all players present) delete channels that have
+   only outgoing invitations pending.
+ */
+void
+comms_invite( CommsCtxt* comms, XWEnv xwe, const NetLaunchInfo* nli,
+              const CommsAddrRec* destAddr )
+{
+    LOG_FUNC();
+    /* See if we have a channel for this address. Then see if we have an
+       invite matching this one, and if not add one. Then trigger a send of
+       it. */
+
+    MsgQueueElem* elem = NULL;
+    XP_PlayerAddr channelNo = 0; /* = findOrMakeChannel( comms, destAddr ); */
+
+    for ( AddressRecord* rec = comms->recs; !!rec; rec = rec->next ) {
+        const CommsAddrRec* addr = &rec->addr;
+        if ( isSameAddr( addr, destAddr ) ) {
+            channelNo = rec->channelNo;
+            // found = XP_TRUE;
+            break;
+        }
+    }
+
+    for ( MsgQueueElem* elem = comms->msgQueueHead; !!elem; elem = elem-> next ) {
+        if ( channelNo == elem->channelNo ) {
+            XP_ASSERT( 0 == elem->msgID );
+            XP_ASSERT( 0 != channelNo );
+            freeElem( comms, elem );
+            XP_LOGFF( "nuked old invite" );
+        }
+    }
+
+    if ( 0 == channelNo ) {
+        channelNo = comms_getChannelSeed(comms) & ~CHANNEL_MASK;
+    }
+
+    /*AddressRecord* rec = */rememberChannelAddress( comms, xwe, channelNo,
+                                                     0, destAddr, 0 );
+    elem = makeInviteElem( comms, xwe, channelNo, nli );
+
+    elem = addToQueue( comms, xwe, elem );
+    sendMsg( comms, xwe, elem, COMMS_CONN_NONE );
+}
+#endif
+
 /* Send a message using the sequentially next MsgID.  Save the message so
  * resend can work. */
 XP_S16
@@ -1680,9 +1813,10 @@ sendMsg( CommsCtxt* comms, XWEnv xwe, MsgQueueElem* elem, const CommsConnType fi
     XP_PlayerAddr channelNo = elem->channelNo;
     CNO_FMT( cbuf, channelNo );
 
+    XP_Bool isInvite = 0 == elem->len;
 #ifdef COMMS_CHECKSUM
-    XP_LOGFF( TAGFMT() "sending message on %s: id: %d; len: %d; sum: %s", TAGPRMS,
-              cbuf, elem->msgID, elem->len, elem->checksum );
+    XP_LOGFF( TAGFMT() "sending message on %s: id: %d; len: %d; sum: %s; isInvite: %s",
+              TAGPRMS, cbuf, elem->msgID, elem->len, elem->checksum, boolToStr(isInvite) );
 #endif
 
     const CommsAddrRec* addrP = NULL;
@@ -1771,12 +1905,36 @@ sendMsg( CommsCtxt* comms, XWEnv xwe, MsgQueueElem* elem, const CommsConnType fi
                                                   typ, gameid, comms->procs.closure );
                     break;
                 }
-                } /* switch */
-            }
-            XP_LOGFF( TAGFMT() "sent %d bytes using typ %s", TAGPRMS, nSent,
-                      ConnType2Str(typ) );
-            if ( nSent > result ) {
-                result = nSent;
+/* <<<<<<< HEAD */
+/*                 } /\* switch *\/ */
+/*             } */
+/*             XP_LOGFF( TAGFMT() "sent %d bytes using typ %s", TAGPRMS, nSent, */
+/*                       ConnType2Str(typ) ); */
+/*             if ( nSent > result ) { */
+/*                 result = nSent; */
+/* ======= */
+
+/*                 if ( 0 ) { */
+/* #ifdef XWFEATURE_COMMS_INVITE */
+/*                 } else if ( isInvite ) { */
+/*                     XP_ASSERT( !!comms->procs.sendInvt ); */
+/*                     NetLaunchInfo* nli = (NetLaunchInfo*)elem->msg; */
+/*                     nSent = (*comms->procs.sendInvt)( xwe, nli, elem->createdStamp, */
+/*                                                       &addr, comms->procs.closure ); */
+/* #endif */
+/*                 } else { */
+/*                     XP_ASSERT( !!comms->procs.sendMsg ); */
+/*                     XP_U32 gameid = gameID( comms ); */
+/*                     logAddr( comms, xwe, &addr, __func__ ); */
+/*                     XP_UCHAR msgNo[16]; */
+/*                     formatMsgNo( comms, elem, msgNo, sizeof(msgNo) ); */
+/*                     nSent = (*comms->procs.sendMsg)( xwe, elem->msg, elem->len, msgNo, */
+/*                                                      elem->createdStamp, &addr, */
+/*                                                      typ, gameid, */
+/*                                                      comms->procs.closure ); */
+/*                 } */
+/*                 break; */
+/* >>>>>>> d9781d21e (snapshot: mqtt invites for gtk work via comms) */
             }
         }
     
@@ -1823,9 +1981,7 @@ resendImpl( CommsCtxt* comms, XWEnv xwe, CommsConnType filter, XP_Bool force,
         success = XP_FALSE;
 
     } else if ( !!comms->msgQueueHead ) {
-        MsgQueueElem* msg;
-
-        for ( msg = comms->msgQueueHead; !!msg; msg = msg->next ) {
+        for ( MsgQueueElem* msg = comms->msgQueueHead; !!msg; msg = msg->next ) {
             XP_S16 len = (*proc)( comms, xwe, msg, filter, closure );
             if ( 0 > len ) {
                 success = XP_FALSE;
@@ -2436,8 +2592,9 @@ validateInitialMessage( CommsCtxt* comms, XWEnv xwe,
                 XP_ASSERT( (*channelNo & CHANNEL_MASK) == 0 );
                 *channelNo |= ++comms->nextChannelNo;
                 CNO_FMT( cbuf1, *channelNo );
-                XP_LOGFF( TAGFMT() "ORd channel onto channelNo: now %s", TAGPRMS, cbuf1 );
-                XP_ASSERT( comms->nextChannelNo <= CHANNEL_MASK );
+                XP_LOGFF( TAGFMT() "ORd channel onto channelNo: now %s", TAGPRMS,
+                          cbuf1 );
+                XP_ASSERT( comms->nextChannelNo <= CHANNEL_ID_MASK );
             }
             rec = rememberChannelAddress( comms, xwe, *channelNo, senderID, addr,
                                           flags );
@@ -2480,7 +2637,8 @@ validateInitialMessage( CommsCtxt* comms, XWEnv xwe,
                     goto errExit;
                 }
             }
-            rec = rememberChannelAddress( comms, xwe, *channelNo, senderID, addr, flags );
+            rec = rememberChannelAddress( comms, xwe, *channelNo, senderID,
+                                          addr, flags );
         }
     }
  errExit:
@@ -2575,8 +2733,10 @@ getCheckChannelSeed( CommsCtxt* comms, XWStreamCtxt* stream, HeaderStuff* stuff
         } else if ( 0 == stuff->channelNo || 0 == channelSeed ) {
             XP_LOGFF( TAGFMT() "one of channelNos still 0", TAGPRMS );
             XP_ASSERT(0);
-        } else if ( (stuff->channelNo & ~CHANNEL_MASK) != (channelSeed & ~CHANNEL_MASK) ) {
-            XP_LOGFF( "channelNos test fails: %x vs %x", stuff->channelNo, channelSeed );
+        } else if ( (stuff->channelNo & ~CHANNEL_MASK)
+                    != (channelSeed & ~CHANNEL_MASK) ) {
+            XP_LOGFF( "channelNos test fails: %x vs %x", stuff->channelNo,
+                      channelSeed );
             messageValid = XP_FALSE;
         }
     }
@@ -2610,8 +2770,9 @@ parseSmallHeader( CommsCtxt* comms, XWEnv xwe, XWStreamCtxt* msgStream,
     XP_ASSERT( 0 < headerLen );
     XP_ASSERT( headerLen <= stream_getSize( msgStream ) );
     if ( headerLen <= stream_getSize( msgStream ) ) {
-        XWStreamCtxt* hdrStream = mem_stream_make_raw( MPPARM(comms->mpool)
-                                                       dutil_getVTManager(comms->dutil));
+        XWStreamCtxt* hdrStream =
+            mem_stream_make_raw( MPPARM(comms->mpool)
+                                 dutil_getVTManager(comms->dutil));
         stream_getFromStream( hdrStream, msgStream, headerLen );
         stuff->connID = 0 == (stuff->flags & NO_CONNID_BIT)
             ? comms->util->gameInfo->gameID : CONN_ID_NONE;
@@ -2714,14 +2875,17 @@ comms_checkIncomingStream( CommsCtxt* comms, XWEnv xwe, XWStreamCtxt* stream,
                 if ( stuff.connID == CONN_ID_NONE ) {
                     /* special case: initial message from client or server */
                     rec = validateInitialMessage( comms, xwe, streamSize > 0, retAddr,
-                                                  senderID, &stuff.channelNo, stuff.flags );
+                                                  senderID, &stuff.channelNo,
+                                                  stuff.flags );
                     state->rec = rec;
                 } else if ( comms->connID == stuff.connID ) {
-                    rec = validateChannelMessage( comms, xwe, retAddr, stuff.channelNo,
-                                                  senderID, stuff.msgID, stuff.lastMsgRcd );
+                    rec = validateChannelMessage( comms, xwe, retAddr,
+                                                  stuff.channelNo, senderID,
+                                                  stuff.msgID, stuff.lastMsgRcd );
                 } else {
                     XP_LOGFF( TAGFMT() "unexpected connID (%x vs %x) ; "
-                              "dropping message", TAGPRMS, comms->connID, stuff.connID );
+                              "dropping message", TAGPRMS, comms->connID,
+                              stuff.connID );
                 }
             }
 
@@ -2881,9 +3045,8 @@ comms_gameJoined( CommsCtxt* comms, XWEnv xwe, const XP_UCHAR* connname, XWHostI
 static void
 sendEmptyMsg( CommsCtxt* comms, XWEnv xwe, AddressRecord* rec )
 {
-    MsgQueueElem* elem = makeElemWithID( comms, xwe, 0, // msgID
-                                         rec, rec? rec->channelNo : 0,
-                                         NULL );
+    MsgQueueElem* elem = makeElemWithID( comms, xwe, 0 /* msgID */, 
+                                         rec, rec? rec->channelNo : 0, NULL );
     (void)sendMsg( comms, xwe, elem, COMMS_CONN_NONE );
     freeElem( comms, elem );
 } /* sendEmptyMsg */
@@ -3712,8 +3875,8 @@ send_via_bt_or_ip( CommsCtxt* comms, XWEnv xwe, BTIPMsgType msgTyp, XP_PlayerAdd
             XP_MEMCPY( &buf[1], data, dlen );
         }
 
-        nSent = (*comms->procs.send)( xwe, buf, dlen+1, msgNo, 0,
-                                      addr, typ, gameID(comms), comms->procs.closure );
+        nSent = (*comms->procs.sendMsg)( xwe, buf, dlen+1, msgNo, 0, addr, typ,
+                                         gameID(comms), comms->procs.closure );
         XP_FREE( comms->mpool, buf );
 
         setHeartbeatTimer( comms );
diff --git a/xwords4/common/comms.h b/xwords4/common/comms.h
index 79b5e1c91..01519443f 100644
--- a/xwords4/common/comms.h
+++ b/xwords4/common/comms.h
@@ -74,11 +74,17 @@ typedef enum {
 # define IF_CH(a)
 #endif
 
-typedef XP_S16 (*TransportSend)( XWEnv xwe, const XP_U8* buf, XP_U16 len,
-                                 const XP_UCHAR* msgNo, XP_U32 createdStamp,
-                                 const CommsAddrRec* addr,
-                                 CommsConnType conType,
-                                 XP_U32 gameID, void* closure );
+#ifdef XWFEATURE_COMMS_INVITE
+typedef XP_S16 (*TransportSendInvt)( XWEnv xwe, const NetLaunchInfo* nli,
+                                     XP_U32 createdStamp,
+                                     const CommsAddrRec* addr, void* closure );
+#endif
+typedef XP_S16 (*TransportSendMsg)( XWEnv xwe, const XP_U8* buf, XP_U16 len,
+                                    const XP_UCHAR* msgNo, XP_U32 createdStamp,
+                                    const CommsAddrRec* addr,
+                                    CommsConnType conType, XP_U32 gameID,
+                                    void* closure );
+
 #ifdef COMMS_HEARTBEAT
 typedef void (*TransportReset)( XWEnv xwe, void* closure );
 #endif
@@ -119,7 +125,10 @@ typedef struct _TransportProcs {
 #else
     XP_U32 flags;
 #endif
-    TransportSend send;
+    TransportSendMsg sendMsg;
+#ifdef XWFEATURE_COMMS_INVITE
+    TransportSendInvt sendInvt;
+#endif
     MsgCountChange countChanged;
 #ifdef COMMS_HEARTBEAT
     TransportReset reset;
@@ -205,7 +214,10 @@ void comms_saveSucceeded( CommsCtxt* comms, XWEnv xwe, XP_U16 saveToken );
 
 void addrFromStream( CommsAddrRec* addr, XWStreamCtxt* stream );
 void addrToStream( XWStreamCtxt* stream, const CommsAddrRec* addr );
-
+#ifdef XWFEATURE_COMMS_INVITE
+void comms_invite( CommsCtxt* comms, XWEnv xwe, const NetLaunchInfo* nli,
+                   const CommsAddrRec* destAddr );
+#endif
 XP_S16 comms_send( CommsCtxt* comms, XWEnv xwe, XWStreamCtxt* stream );
 XP_S16 comms_resendAll( CommsCtxt* comms, XWEnv xwe, CommsConnType filter,
                         XP_Bool force );
diff --git a/xwords4/common/comtypes.h b/xwords4/common/comtypes.h
index a741a5e3c..4f594bec5 100644
--- a/xwords4/common/comtypes.h
+++ b/xwords4/common/comtypes.h
@@ -175,9 +175,7 @@ typedef struct PoolContext PoolContext;
 typedef struct XW_UtilCtxt XW_UtilCtxt;
 typedef struct XW_DUtilCtxt XW_DUtilCtxt;
 
-/* Low two bits treated as channel, third as short-term flag indicating
- * sender's role; rest can be random to aid detection of duplicate packets. */
-#define CHANNEL_MASK 0x0003
+/* Opaque bitfield type meant to be parsed only inside comms.c  */
 typedef XP_U16 XP_PlayerAddr;
 
 typedef enum {
diff --git a/xwords4/linux/Makefile b/xwords4/linux/Makefile
index 7c84f138f..b5707293e 100644
--- a/xwords4/linux/Makefile
+++ b/xwords4/linux/Makefile
@@ -132,6 +132,7 @@ DEFINES += -DCOMMS_XPORT_FLAGSPROC
 DEFINES += -DINITIAL_CLIENT_VERS=3
 DEFINES += -DCOMMON_LAYOUT
 DEFINES += -DNATIVE_NLI
+DEFINES += -DXWFEATURE_COMMS_INVITE
 # DEFINES += -DRELAY_VIA_HTTP
 
 # MAX_ROWS controls STREAM_VERS_BIGBOARD and with it move hashing
diff --git a/xwords4/linux/cursesboard.c b/xwords4/linux/cursesboard.c
index c303258a5..6cc8a6b2e 100644
--- a/xwords4/linux/cursesboard.c
+++ b/xwords4/linux/cursesboard.c
@@ -381,7 +381,10 @@ commonInit( CursesBoardState* cbState, sqlite3_int64 rowid,
     cGlobals->addAcceptor = curses_socket_acceptor;
 
     bGlobals->procs.closure = cGlobals;
-    bGlobals->procs.send = LINUX_SEND;
+    bGlobals->procs.sendMsg = linux_send;
+#ifdef XWFEATURE_COMMS_INVITE
+    bGlobals->procs.sendInvt = linux_send_invt;
+#endif
 #ifdef COMMS_HEARTBEAT
     bGlobals->procs.reset = linux_reset;
 #endif
@@ -1215,7 +1218,7 @@ inviteList( CommonGlobals* cGlobals, CommsAddrRec* addr, GSList* invitees,
                 MQTTDevID devID;
                 const gchar* str = g_slist_nth_data( invitees, ii );
                 if ( strToMQTTCDevID( str, &devID ) ) {
-                    mqttc_invite( params, &nli, &devID );
+                    mqttc_invite( params, 0, &nli, &devID );
                 } else {
                     XP_LOGFF( "unable to convert devid %s", str );
                 }
@@ -1261,11 +1264,19 @@ handleInvite( void* closure, int XP_UNUSED(key) )
     } else if ( inviteList( cGlobals, &selfAddr, params->connInfo.mqtt.inviteeDevIDs, COMMS_CONN_MQTT ) ) {
         /* do nothing */
     /* Try sending to self, using the phone number or relayID of this device */
+/* <<<<<<< HEAD */
     } else if ( addr_hasType( &selfAddr, COMMS_CONN_SMS ) ) {
         linux_sms_invite( params, &nli, selfAddr.u.sms.phone, selfAddr.u.sms.port );
     } else if ( addr_hasType( &selfAddr, COMMS_CONN_MQTT ) ) {
         mqttc_invite( params, &nli, mqttc_getDevID( params ) );
     } else if ( addr_hasType( &selfAddr, COMMS_CONN_RELAY ) ) {
+/* ======= */
+/*     } else if ( addr_hasType( &addr, COMMS_CONN_SMS ) ) { */
+/*         linux_sms_invite( params, &nli, addr.u.sms.phone, addr.u.sms.port ); */
+/*     } else if ( addr_hasType( &addr, COMMS_CONN_MQTT ) ) { */
+/*         mqttc_invite( params, 0, &nli, mqttc_getDevID( params ) ); */
+/*     } else if ( addr_hasType( &addr, COMMS_CONN_RELAY ) ) { */
+/* >>>>>>> d9781d21e (snapshot: mqtt invites for gtk work via comms) */
         XP_U32 relayID = linux_getDevIDRelay( params );
         if ( 0 != relayID ) {
             relaycon_invite( params, relayID, NULL, &nli );
diff --git a/xwords4/linux/gtkboard.c b/xwords4/linux/gtkboard.c
index 90232d86f..b9528434c 100644
--- a/xwords4/linux/gtkboard.c
+++ b/xwords4/linux/gtkboard.c
@@ -487,7 +487,10 @@ static void
 setTransportProcs( TransportProcs* procs, GtkGameGlobals* globals ) 
 {
     procs->closure = globals;
-    procs->send = LINUX_SEND;
+    procs->sendMsg = linux_send;
+#ifdef XWFEATURE_COMMS_INVITE
+    procs->sendInvt = linux_send_invt;
+#endif
 #ifdef COMMS_XPORT_FLAGSPROC
     procs->getFlags = gtk_getFlags;
 #endif
@@ -844,7 +847,10 @@ new_game_impl( GtkGameGlobals* globals, XP_Bool fireConnDlg )
 #endif
         TransportProcs procs = {
             .closure = globals,
-            .send = LINUX_SEND,
+            .sendMsg = linux_send,
+#ifdef XWFEATURE_COMMS_INVITE
+            .sendInvt = linux_send_invt,
+#endif
 #ifdef COMMS_HEARTBEAT
             .reset = linux_reset,
 #endif
@@ -1424,8 +1430,8 @@ static void
 send_invites( CommonGlobals* cGlobals, XP_U16 nPlayers,
               const CommsAddrRec* destAddr )
 {
-    CommsAddrRec myAddr = {0};
     CommsCtxt* comms = cGlobals->game.comms;
+    CommsAddrRec myAddr = {0};
     XP_ASSERT( comms );
     comms_getSelfAddr( comms, &myAddr );
 
@@ -1433,11 +1439,13 @@ send_invites( CommonGlobals* cGlobals, XP_U16 nPlayers,
 
     NetLaunchInfo nli = {0};    /* include everything!!! */
     nli_init( &nli, cGlobals->gi, &myAddr, nPlayers, forceChannel );
+#ifdef XWFEATURE_RELAY
     if ( addr_hasType( &myAddr, COMMS_CONN_RELAY ) ) {
         XP_UCHAR buf[32];
         snprintf( buf, sizeof(buf), "%X", makeRandomInt() );
         nli_setInviteID( &nli, buf ); /* PENDING: should not be relay only!!! */
     }
+#endif
     // nli_setDevID( &nli, linux_getDevIDRelay( cGlobals->params ) );
 
     if ( addr_hasType( &myAddr, COMMS_CONN_MQTT ) ) {
@@ -1457,6 +1465,9 @@ send_invites( CommonGlobals* cGlobals, XP_U16 nPlayers,
     }
 #endif
 
+#ifdef XWFEATURE_COMMS_INVITE
+    comms_invite( comms, NULL_XWE, &nli, destAddr );
+#else
     if ( !!destAddr && '\0' != destAddr->u.sms.phone[0] && 0 < destAddr->u.sms.port ) {
         gchar gameName[64];
         snprintf( gameName, VSIZE(gameName), "Game %d", cGlobals->gi->gameID );
@@ -1464,16 +1475,17 @@ send_invites( CommonGlobals* cGlobals, XP_U16 nPlayers,
         linux_sms_invite( cGlobals->params, &nli,
                           destAddr->u.sms.phone, destAddr->u.sms.port );
     }
-#ifdef XWFEATURE_RELAY
+# ifdef XWFEATURE_RELAY
     if ( 0 != relayDevID || !!relayID ) {
         XP_ASSERT( 0 != relayDevID || (!!relayID && !!relayID[0]) );
         relaycon_invite( cGlobals->params, relayDevID, relayID, &nli );
     }
-#endif
+# endif
 
     if ( addr_hasType( destAddr, COMMS_CONN_MQTT ) ) {
-        mqttc_invite( cGlobals->params, &nli, &destAddr->u.mqtt.devID );
+        mqttc_invite( cGlobals->params, 0, &nli, &destAddr->u.mqtt.devID );
     }
+#endif
 
     /* while ( gtkaskm( "Invite how many and how?", infos, VSIZE(infos) ) ) {  */
     /*     int nPlayers = atoi( countStr ); */
diff --git a/xwords4/linux/linuxmain.c b/xwords4/linux/linuxmain.c
index 29f799aeb..c8bb51ddc 100644
--- a/xwords4/linux/linuxmain.c
+++ b/xwords4/linux/linuxmain.c
@@ -1494,6 +1494,28 @@ linux_send( XWEnv XP_UNUSED(xwe), const XP_U8* buf, XP_U16 buflen,
     return nSent;
 } /* linux_send */
 
+XP_S16
+linux_send_invt( XWEnv XP_UNUSED(xwe), const NetLaunchInfo* nli,
+                 XP_U32 createdStamp,
+                 const CommsAddrRec* destAddr, void* closure )
+{
+    XP_S16 nSent = -1;
+    CommonGlobals* cGlobals = (CommonGlobals*)closure;
+
+    CommsConnType typ;
+    for ( XP_U32 st = 0; addr_iter( destAddr, &typ, &st ); ) {
+        switch ( typ ) {
+        case COMMS_CONN_MQTT:
+            mqttc_invite( cGlobals->params, createdStamp, nli,
+                          &destAddr->u.mqtt.devID );
+            break;
+        default:
+            XP_ASSERT(0);
+        }
+    }
+    return nSent;
+}
+
 static int
 blocking_read( int fd, unsigned char* buf, const int len )
 {
diff --git a/xwords4/linux/linuxmain.h b/xwords4/linux/linuxmain.h
index 6ee12360e..9ad7bf4c8 100644
--- a/xwords4/linux/linuxmain.h
+++ b/xwords4/linux/linuxmain.h
@@ -41,12 +41,11 @@ int initListenerSocket( int port );
 XP_S16 linux_send( XWEnv xwe, const XP_U8* buf, XP_U16 buflen,
                    const XP_UCHAR* msgNo, XP_U32 createdStamp,
                    const CommsAddrRec* addrRec,
-                   CommsConnType conType, XP_U32 gameID, void* closure );
-#ifndef XWFEATURE_STANDALONE_ONLY
-# define LINUX_SEND linux_send
-#else
-# define LINUX_SEND NULL
-#endif
+                   CommsConnType conType, XP_U32 gameID,
+                   void* closure );
+XP_S16 linux_send_invt( XWEnv xwe, const NetLaunchInfo* nli,
+                        XP_U32 createdStamp,
+                        const CommsAddrRec* addr, void* closure );
 
 #ifdef COMMS_HEARTBEAT
 void linux_reset( void* closure );
diff --git a/xwords4/linux/mqttcon.c b/xwords4/linux/mqttcon.c
index 0b177e2c7..8ffe1a48a 100644
--- a/xwords4/linux/mqttcon.c
+++ b/xwords4/linux/mqttcon.c
@@ -249,7 +249,8 @@ mqttc_getDevIDStr( LaunchParams* params )
 }
 
 void
-mqttc_invite( LaunchParams* params, NetLaunchInfo* nli, const MQTTDevID* invitee )
+mqttc_invite( LaunchParams* params, XP_U32 timestamp, const NetLaunchInfo* nli,
+              const MQTTDevID* invitee )
 {
     MQTTConStorage* storage = getStorage( params );
 #ifdef DEBUG
@@ -257,6 +258,7 @@ mqttc_invite( LaunchParams* params, NetLaunchInfo* nli, const MQTTDevID* invitee
     XP_LOGFF( "need to send to %s", formatMQTTDevID(invitee, buf, sizeof(buf) ) );
     XP_ASSERT( 16 == strlen(buf) );
 #endif
+    XP_USE( timestamp );
 
     XWStreamCtxt* stream = mem_stream_make_raw( MPPARM(params->mpool)
                                                 params->vtMgr );
diff --git a/xwords4/linux/mqttcon.h b/xwords4/linux/mqttcon.h
index 72bcc031d..6b1658045 100644
--- a/xwords4/linux/mqttcon.h
+++ b/xwords4/linux/mqttcon.h
@@ -28,7 +28,8 @@ void mqttc_cleanup( LaunchParams* params );
 
 const MQTTDevID* mqttc_getDevID( LaunchParams* params );
 const gchar* mqttc_getDevIDStr( LaunchParams* params );
-void mqttc_invite( LaunchParams* params, NetLaunchInfo*  nli, const MQTTDevID* mqttInvitee );
+void mqttc_invite( LaunchParams* params, XP_U32 timestamp,
+                   const NetLaunchInfo* nli, const MQTTDevID* mqttInvitee );
 XP_S16 mqttc_send( LaunchParams* params, XP_U32 gameID, XP_U32 timestamp,
                    const XP_U8* buf, XP_U16 len, const MQTTDevID* addressee );
 void mqttc_notifyGameGone( LaunchParams* params, const MQTTDevID* addressee, XP_U32 gameID );