People expect that if "hasvoicemail" is set in users.conf, even if "mailbox"

isn't set, that SIP will detect a mailbox.
(closes issue #12855)
 Reported by: PLL
 Patches: 
       20080614__bug12855__2.diff.txt uploaded by Corydon76 (license 14)
 Tested by: PLL


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@123110 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -16841,6 +16841,12 @@ static struct sip_peer *build_peer(const char *name, struct ast_variable *v, str
 			ast_copy_string(peer->mohsuggest, v->value, sizeof(peer->mohsuggest));
 		} else if (!strcasecmp(v->name, "mailbox")) {
 			ast_copy_string(peer->mailbox, v->value, sizeof(peer->mailbox));
+		} else if (!strcasecmp(v->name, "hasvoicemail")) {
+			/* People expect that if 'hasvoicemail' is set, that the mailbox will
+			 * be also set, even if not explicitly specified. */
+			if (ast_true(v->value) && ast_strlen_zero(peer->mailbox)) {
+				ast_copy_string(peer->mailbox, name, sizeof(peer->mailbox));
+			}
 		} else if (!strcasecmp(v->name, "subscribemwi")) {
 			ast_set2_flag(&peer->flags[1], ast_true(v->value), SIP_PAGE2_SUBSCRIBEMWIONLY);
 		} else if (!strcasecmp(v->name, "vmexten")) {