diff --git a/xwords4/android/XWords4/src/org/eehouse/android/xw4/SMSService.java b/xwords4/android/XWords4/src/org/eehouse/android/xw4/SMSService.java
index d8460e01b..e8f1c8d71 100644
--- a/xwords4/android/XWords4/src/org/eehouse/android/xw4/SMSService.java
+++ b/xwords4/android/XWords4/src/org/eehouse/android/xw4/SMSService.java
@@ -45,7 +45,9 @@ import org.eehouse.android.xw4.jni.XwJNI;
 
 public class SMSService extends Service {
 
-    private static final String PUBLIC_HEADER = "_XW4";
+    private static final String PUBLIC_HEADER = "-XW4 ";
+    private static final String INSTALL_URL = "http://eehouse.org/_/aa.htm ";
+    private static final int MAX_SMS_LEN = 140; // ??? differs by network
 
     private static final int MAX_LEN_TEXT = 100;
     private static final int HANDLE = 1;
@@ -116,14 +118,21 @@ public class SMSService extends Service {
 
     public static String toPublicFmt( String msg )
     {
-        return PUBLIC_HEADER + msg;
+        String result;
+        int msglen = msg.length() + PUBLIC_HEADER.length();
+        int urllen = INSTALL_URL.length();
+        result = String.format( "%s%s%s", PUBLIC_HEADER, 
+                                msglen + urllen < MAX_SMS_LEN ? INSTALL_URL : "",
+                                msg );
+        return result;
     }
 
     public static String fromPublicFmt( String msg )
     {
         String result = null;
         if ( msg.startsWith( PUBLIC_HEADER ) ) {
-            result = msg.substring( PUBLIC_HEADER.length() );
+            int index = msg.lastIndexOf( " " );
+            result = msg.substring( index + 1 );
         }
         return result;
     }