chan_sip: Remember SDP negotiation on SIP_CODEC_INBOUND.

After a SIP_CODEC_INBOUND in the dialplan, do not continue with cached formats
but remember the joint format. Cached formats contain default parameters,
often create an empty fmtp line. However, a joint format might have passed
format_get_joint(.) in a res_format_attr_* module (like Opus Codec) and
contain the resulting format parameters from a SDP negotiation.

ASTERISK-26691 #close

Change-Id: I35712d98a793d4c3efdd156cec57deab9014b1dc

channels/chan_sip.c

@@ -7369,6 +7369,12 @@ static void try_suggested_sip_codec(struct sip_pvt *p)
 		ao2_ref(fmt, -1);
 	}
+
+	/* The original joint formats may have contained negotiated parameters (fmtp)
+	 * like the Opus Codec or iLBC 20. The cached formats contain the default
+	 * parameters, which could be different than the negotiated (joint) result. */
+	ast_format_cap_replace_from_cap(p->jointcaps, original_jointcaps, AST_MEDIA_TYPE_UNKNOWN);
+
 	ao2_ref(original_jointcaps, -1);
 	return;
  }