Beta support: MMS on chatty/mmsd on Modem Manager - help/testing wanted!

[raph]

Hello,

I compiled chatty from branch wip/sadiq/mm-account and mmsd-tng.

After sending an mms using mmsd/test/send-message as documented there: https://source.puri.sm/Librem5/purple-mm...ote_132496

Chatty outputs the following, and crashes immediatly:

```
10:20:43.1745         chatty-mmsd[ 4968]: WARNING: Your SIM or Modem does not support modem manger's number! Please f
ile a bug report
10:20:47.7195         chatty-mmsd[ 4968]:  ERROR: Receieved Modem Number +33633153377 different than current modem n
umber
```

I managed to get it working with this patch:

```
diff --git a/src/users/chatty-mmsd.c b/src/users/chatty-mmsd.c
index 16f9d15..a7ee078 100644
--- a/src/users/chatty-mmsd.c
+++ b/src/users/chatty-mmsd.c
@@ -1825,7 +1825,7 @@ chatty_mmsd_load (ChattyMmsd  *self,
    g_debug ("modem_number: %s", self->modem_number);
    } else {
      g_warning ("Your SIM or Modem does not support modem manger's number! Please file a bug report");
-      self->modem_number = g_strdup ("+1XXXXXXXXXX");
+      self->modem_number = g_strdup ("");
      g_debug ("Making Dummy modem number: %s", self->modem_number);
    } 
```

I'm using a SIM card from SFR (France) in a Pinephone. If I can be of any help I'd be glad to.

(by the way, heads up on the typo "manger" -> "manager", and on the indentation in this function).

Thanks for your work on this :-)