--- asterisk-11.0.1/channels/chan_sip.c	2012-11-05 11:29:46.000000000 -0500
+++ asterisk-11.0.1/channels/chan_sip.c-new	2012-11-22 12:58:04.527860807 -0500
@@ -27126,7 +27126,7 @@
 
 		accept = __get_header(req, "Accept", &start);
 		while (!found_supported && !ast_strlen_zero(accept)) {
-			found_supported = strcmp(accept, "application/simple-message-summary") ? 0 : 1;
+			found_supported = strstr(accept, "application/simple-message-summary") ? 1 : 0;
 			if (!found_supported && (option_debug > 2)) {
 				ast_debug(1, "Received SIP mailbox subscription for unknown format: %s\n", accept);
 			}