diff --git a/CHANGES b/CHANGES
index 986c132e30..4f44c1412a 100644
--- a/CHANGES
+++ b/CHANGES
@@ -24,6 +24,13 @@ Chan_local changes
  * Added a manager event "LocalBridge" for local channel call bridges between
    the two pseudo-channels created.
 
+Codec changes
+-------------
+ * Codec lists may now be modified by the '!' character, to allow succinct
+   specification of a list of codecs allowed and disallowed, without the
+   requirement to use two different keywords.  For example, to specify all
+   codecs except g729 and g723, one need only specify allow=all,!g729,!g723.
+
 ------------------------------------------------------------------------------
 --- Functionality changes from Asterisk 1.8 to Asterisk 10 -------------------
 ------------------------------------------------------------------------------
diff --git a/configs/sip.conf.sample b/configs/sip.conf.sample
index fb487dba66..7c04a4a0f5 100644
--- a/configs/sip.conf.sample
+++ b/configs/sip.conf.sample
@@ -1216,10 +1216,14 @@ srvlookup=yes                   ; Enable DNS SRV lookups on outbound calls
         allow=gsm
         allow=g723
         allow=ulaw
+        ; Or, more simply:
+        ;allow=!all,ilbc,g729,gsm,g723,ulaw
 
 [ulaw-phone](!)                   ; and another one for ulaw-only
         disallow=all
         allow=ulaw
+        ; Again, more simply:
+        ;allow=!all,ulaw
 
 ; and finally instantiate a few phones
 ;
diff --git a/contrib/realtime/mysql/iaxfriends.sql b/contrib/realtime/mysql/iaxfriends.sql
index 3b3bbb3c79..f01fd73ffa 100644
--- a/contrib/realtime/mysql/iaxfriends.sql
+++ b/contrib/realtime/mysql/iaxfriends.sql
@@ -37,8 +37,7 @@ CREATE TABLE `iaxfriends` (
   `transfer` varchar(10) NULL, -- mediaonly/yes/no
   `jitterbuffer` varchar(3) NULL, -- yes/no
   `forcejitterbuffer` varchar(3) NULL, -- yes/no
-  `disallow` varchar(40) NULL, -- all/{list-of-codecs}
-  `allow` varchar(40) NULL, -- all/{list-of-codecs}
+  `allow` varchar(200) NULL, -- all/{list-of-codecs}
   `codecpriority` varchar(40) NULL, 
   `qualify` varchar(10) NULL, -- yes/no/{number of milliseconds}
   `qualifysmoothing` varchar(10) NULL, -- yes/no
diff --git a/contrib/realtime/mysql/sipfriends.sql b/contrib/realtime/mysql/sipfriends.sql
index 12047d399b..07cd8788aa 100644
--- a/contrib/realtime/mysql/sipfriends.sql
+++ b/contrib/realtime/mysql/sipfriends.sql
@@ -28,8 +28,7 @@ CREATE TABLE IF NOT EXISTS `sipfriends` (
       `callgroup` varchar(40) DEFAULT NULL,
       `pickupgroup` varchar(40) DEFAULT NULL,
       `language` varchar(40) DEFAULT NULL,
-      `allow` varchar(40) DEFAULT NULL,
-      `disallow` varchar(40) DEFAULT NULL,
+      `allow` varchar(200) DEFAULT NULL,
       `insecure` varchar(40) DEFAULT NULL,
       `trustrpid` enum('yes','no') DEFAULT NULL,
       `progressinband` enum('yes','no','never') DEFAULT NULL,
diff --git a/contrib/realtime/postgresql/realtime.sql b/contrib/realtime/postgresql/realtime.sql
index 74b895738f..fb474ebbe2 100644
--- a/contrib/realtime/postgresql/realtime.sql
+++ b/contrib/realtime/postgresql/realtime.sql
@@ -61,8 +61,7 @@ rtpholdtimeout character varying(3),
 secret character varying(80),
 "type" character varying DEFAULT 'friend' NOT NULL,
 username character varying(80) DEFAULT '' NOT NULL,
-disallow character varying(100) DEFAULT 'all',
-allow character varying(100) DEFAULT 'g729;ilbc;gsm;ulaw;alaw',
+allow character varying(200) DEFAULT '!all,g729,ilbc,gsm,ulaw,alaw',
 musiconhold character varying(100),
 regseconds bigint DEFAULT 0::bigint NOT NULL,
 ipaddr character varying(40) DEFAULT '' NOT NULL,
diff --git a/main/frame.c b/main/frame.c
index b664e2e849..4a91096949 100644
--- a/main/frame.c
+++ b/main/frame.c
@@ -730,13 +730,18 @@ void ast_frame_dump(const char *name, struct ast_frame *f, char *prefix)
 
 int ast_parse_allow_disallow(struct ast_codec_pref *pref, struct ast_format_cap *cap, const char *list, int allowing) 
 {
-	int errors = 0, framems = 0, all = 0;
+	int errors = 0, framems = 0, all = 0, iter_allowing;
 	char *parse = NULL, *this = NULL, *psize = NULL;
 	struct ast_format format;
 
 	parse = ast_strdupa(list);
 	while ((this = strsep(&parse, ","))) {
+		iter_allowing = allowing;
 		framems = 0;
+		if (*this == '!') {
+			this++;
+			iter_allowing = !allowing;
+		}
 		if ((psize = strrchr(this, ':'))) {
 			*psize++ = '\0';
 			ast_debug(1, "Packetization for codec: %s is %s\n", this, psize);
@@ -750,13 +755,13 @@ int ast_parse_allow_disallow(struct ast_codec_pref *pref, struct ast_format_cap
 		all = strcasecmp(this, "all") ? 0 : 1;
 
 		if (!all && !ast_getformatbyname(this, &format)) {
-			ast_log(LOG_WARNING, "Cannot %s unknown format '%s'\n", allowing ? "allow" : "disallow", this);
+			ast_log(LOG_WARNING, "Cannot %s unknown format '%s'\n", iter_allowing ? "allow" : "disallow", this);
 			errors++;
 			continue;
 		}
 
 		if (cap) {
-			if (allowing) {
+			if (iter_allowing) {
 				if (all) {
 					ast_format_cap_add_all(cap);
 				} else {
@@ -773,13 +778,13 @@ int ast_parse_allow_disallow(struct ast_codec_pref *pref, struct ast_format_cap
 
 		if (pref) {
 			if (!all) {
-				if (allowing) {
+				if (iter_allowing) {
 					ast_codec_pref_append(pref, &format);
 					ast_codec_pref_setsize(pref, &format, framems);
 				} else {
 					ast_codec_pref_remove(pref, &format);
 				}
-			} else if (!allowing) {
+			} else if (!iter_allowing) {
 				memset(pref, 0, sizeof(*pref));
 			}
 		}