diff -uNr asterisk-1.6.2.0.ORIG/channels/chan_dahdi.c asterisk-1.6.2.0/channels/chan_dahdi.c
--- asterisk-1.6.2.0.ORIG/channels/chan_dahdi.c	2010-01-04 13:57:12.000000000 +0000
+++ asterisk-1.6.2.0/channels/chan_dahdi.c	2010-01-04 14:08:54.000000000 +0000
@@ -8419,6 +8419,7 @@
 						}
 						if (i & DAHDI_IOMUX_SIGEVENT) {
 							res = dahdi_get_event(p->subs[idx].dfd);
+							if (res == DAHDI_EVENT_NOALARM) p->inalarm = 0;
 							ast_log(LOG_NOTICE, "Got event %d (%s)...\n", res, event2str(res));
 
 							if (p->cid_signalling == CID_SIG_V23_JP) {
@@ -8521,6 +8522,7 @@
 							if (i & DAHDI_IOMUX_SIGEVENT) {
 								res = dahdi_get_event(p->subs[idx].dfd);
 								ast_log(LOG_NOTICE, "Got event %d (%s)...\n", res, event2str(res));
+								if (res == DAHDI_EVENT_NOALARM) p->inalarm = 0;
 								res = 0;
 								/* Let us detect distinctive ring */
 
@@ -8670,6 +8672,7 @@
 						if (i & DAHDI_IOMUX_SIGEVENT) {
 							res = dahdi_get_event(p->subs[idx].dfd);
 							ast_log(LOG_NOTICE, "Got event %d (%s)...\n", res, event2str(res));
+							if (res == DAHDI_EVENT_NOALARM) p->inalarm = 0;
 							/* If we get a PR event, they hung up while processing calerid */
 							if ( res == DAHDI_EVENT_POLARITY && p->hanguponpolarityswitch && p->polarity == POLARITY_REV) {
 								ast_log(LOG_DEBUG, "Hanging up due to polarity reversal on channel %d while detecting callerid\n", p->channel);
@@ -8739,6 +8742,7 @@
 							if (i & DAHDI_IOMUX_SIGEVENT) {
 								res = dahdi_get_event(p->subs[idx].dfd);
 								ast_log(LOG_NOTICE, "Got event %d (%s)...\n", res, event2str(res));
+								if (res == DAHDI_EVENT_NOALARM) p->inalarm = 0;
 								res = 0;
 								/* Let us detect callerid when the telco uses distinctive ring */