Index: channels/chan_iax2.c
===================================================================
RCS file: /usr/cvsroot/asterisk/channels/chan_iax2.c,v
retrieving revision 1.237
diff -u -r1.237 chan_iax2.c
--- channels/chan_iax2.c	14 Jan 2005 21:10:16 -0000	1.237
+++ channels/chan_iax2.c	15 Jan 2005 00:26:40 -0000
@@ -2367,6 +2367,38 @@
 	return tmp;
 }
 
+/* Sub-function of iax2_call. Determines preferred format, and appends it to the iax_ie_data. */
+static void iax2_call_set_preferred_codec(struct iax_ie_data *ie_data, struct ast_channel *channel, struct chan_iax2_pvt* pvt)
+{
+	/*  Shares code with chan_sip.c::sip_call */
+	/*	PREFERRED_CODEC can override the selection for preferred codec. 
+		Be sure to set the var _PREFERRED_CODEC in the dialplan (note leading underscore), 
+		    so that the variable is passed onto the new channel. */
+	char *preferred_codec; 
+	int format = channel->nativeformats;			/* Default to using the current native format */
+
+	preferred_codec = pbx_builtin_getvar_helper(channel, "PREFERRED_CODEC");
+	if (preferred_codec && !ast_strlen_zero(preferred_codec)) {
+		int override_format = ast_getformatbyname(preferred_codec);
+		if (override_format) {
+			if (override_format & pvt->capability) {
+				format = override_format;
+				if (option_verbose > 2) { 
+					ast_verbose(VERBOSE_PREFIX_3 "PREFERRED_CODEC variable overriding preferred format for this call to %s\n", preferred_codec);
+				}
+			} else {
+				ast_log(LOG_NOTICE, 
+					"Ignoring PREFERRED_CODEC variable: Cannot use because current capabilites (0x%x) do not include %s (0x%x).\n",  
+					pvt->capability, preferred_codec, override_format);
+			}
+		} else {
+			ast_log(LOG_NOTICE, "Ignoring PREFERRED_CODEC variable: Unknown codec '%s'.\n", preferred_codec);
+		}
+	}
+	
+	iax_ie_append_int(ie_data, IAX_IE_FORMAT, format);
+}
+
 static int iax2_call(struct ast_channel *c, char *dest, int timeout)
 {
 	struct sockaddr_in sin;
@@ -2499,7 +2531,7 @@
 		} else
 			strncpy(iaxs[callno]->secret, secret, sizeof(iaxs[callno]->secret)-1);
 	}
-	iax_ie_append_int(&ied, IAX_IE_FORMAT, c->nativeformats);
+	iax2_call_set_preferred_codec(&ied, c, iaxs[callno]);
 	iax_ie_append_int(&ied, IAX_IE_CAPABILITY, iaxs[callno]->capability);
 	iax_ie_append_short(&ied, IAX_IE_ADSICPE, c->adsicpe);
 	iax_ie_append_int(&ied, IAX_IE_DATETIME, iax2_datetime(tz));
Index: channels/chan_sip.c
===================================================================
RCS file: /usr/cvsroot/asterisk/channels/chan_sip.c,v
retrieving revision 1.631
diff -u -r1.631 chan_sip.c
--- channels/chan_sip.c	13 Jan 2005 20:26:33 -0000	1.631
+++ channels/chan_sip.c	15 Jan 2005 00:26:49 -0000
@@ -1393,7 +1393,6 @@
 		return -1;
 	}
 	/* Check whether there is vxml_url, distinctive ring variables */
-
 	headp=&ast->varshead;
 	AST_LIST_TRAVERSE(headp,current,entries) {
 		/* Check whether there is a VXML_URL variable */
@@ -1433,6 +1432,28 @@
 	if ( res != -1 ) {
 		p->callingpres = ast->cid.cid_pres;
 		p->jointcapability = p->capability;
+
+		/* Handle PREFERRED_CODEC override. Ensure dialplan sets var with leading underscore so it gets passed. */
+		/* Shares code with chan_iax2.c::iax2_call_set_preferred_codec */
+		char *preferred_codec = pbx_builtin_getvar_helper(ast, "PREFERRED_CODEC");
+		if (preferred_codec && !ast_strlen_zero(preferred_codec)) {
+			int override_format = ast_getformatbyname(preferred_codec);
+			if (override_format) {
+				if (override_format & p->capability) {
+					p->prefcodec = override_format;
+					if (option_verbose > 2) { 
+						ast_verbose(VERBOSE_PREFIX_3 "PREFERRED_CODEC variable overriding preferred format for this call to %s\n", preferred_codec);
+					}
+				} else {
+					ast_log(LOG_NOTICE, 
+						"Ignoring PREFERRED_CODEC variable: Cannot use because current capabilites (0x%x) do not include %s (0x%x).\n",  
+						p->capability, preferred_codec, override_format);
+				}
+			} else {
+				ast_log(LOG_NOTICE, "Ignoring PREFERRED_CODEC variable: Unknown codec '%s'.\n", preferred_codec);
+			}
+		}
+
 		transmit_invite(p, "INVITE", 1, NULL, NULL, vxml_url,distinctive_ring, osptoken, addsipheaders, 1);
 		if (p->maxtime) {
 			/* Initialize auto-congest time */
@@ -3343,6 +3364,7 @@
 	add_line(req, tmp);
 	return 0;
 }
+
 
 /*--- add_sdp: Add Session Description Protocol message ---*/
 static int add_sdp(struct sip_request *resp, struct sip_pvt *p)