Index: channels/chan_zap.c
===================================================================
--- channels/chan_zap.c	(revision 49783)
+++ channels/chan_zap.c	(working copy)
@@ -954,6 +954,13 @@
 	return 0;
 }
 
+static int zt_get_history(int fd, void *buf, int buf_size)
+{
+	struct zt_history hist;
+	hist.buf=buf;
+	hist.len=buf_size;
+	return ioctl(fd, ZT_GET_HISTORY, &hist);
+}
 
 static int alloc_sub(struct zt_pvt *p, int x)
 {
@@ -6082,6 +6089,118 @@
 		if (p->use_callerid && (p->cid_signalling == CID_SIG_SMDI && smdi_msg)) {
 	     		number = smdi_msg->calling_st;
 
+		/* Check to see if caller ID needs to be extracted from
+		 * the history buffer */
+		} else if (p->use_callerid && p->cid_start == CID_START_USEHIST) {
+			ast_log(LOG_DEBUG,"Using history buffer to extract caller ID\n");
+			cs = callerid_new(p->cid_signalling);
+			if (cs) {
+				unsigned char cidbuf[32768];
+				res=0;
+
+				res = zt_get_history(p->subs[index].zfd,cidbuf,sizeof(cidbuf));
+				if(res<0) {
+					ast_log(LOG_ERROR,"zt_get_history failed: %s\n", strerror(errno));
+				} else {
+					res=callerid_feed(cs,cidbuf,sizeof(cidbuf),AST_LAW(p));
+					if (res < 0) {
+						ast_log(LOG_WARNING, "CallerID feed failed: %s\n", strerror(errno));
+					}
+				}
+
+				if(res==1) {
+					callerid_get(cs, &name, &number, &flags);
+					if (option_debug) 
+						ast_log(LOG_DEBUG, "CallerID number: %s, name: %s, flags=%d\n", number, name, flags);
+				}
+			}
+			if (p->usedistinctiveringdetection == 1) {
+#if 1
+				bump_gains(p);
+#endif				
+				len = 0;
+				distMatches = 0;
+				/* Clear the current ring data array so we dont have old data in it. */
+				for (receivedRingT=0; receivedRingT < 3; receivedRingT++) {
+					curRingData[receivedRingT] = 0;
+				}
+				receivedRingT = 0;
+				counter = 0;
+				counter1 = 0;
+				/* Check to see if context is what it should be, if not set to be. */
+				if (strcmp(p->context,p->defcontext) != 0) {
+					strncpy(p->context, p->defcontext, sizeof(p->context)-1);
+					strncpy(chan->context,p->defcontext,sizeof(chan->context)-1);
+				}
+
+				for(;;) {	
+					i = ZT_IOMUX_READ | ZT_IOMUX_SIGEVENT;
+					if ((res = ioctl(p->subs[index].zfd, ZT_IOMUX, &i)))	{
+						ast_log(LOG_WARNING, "I/O MUX failed: %s\n", strerror(errno));
+						callerid_free(cs);
+						ast_hangup(chan);
+						return NULL;
+					}
+					if (i & ZT_IOMUX_SIGEVENT) {
+						res = zt_get_event(p->subs[index].zfd);
+						ast_log(LOG_NOTICE, "Got event %d (%s)...\n", res, event2str(res));
+						res = 0;
+						/* Let us detect distinctive ring */
+
+						curRingData[receivedRingT] = p->ringt;
+
+						if (p->ringt < ringt_base/2)
+							break;
+						++receivedRingT; /* Increment the ringT counter so we can match it against
+								values in zapata.conf for distinctive ring */
+					} else if (i & ZT_IOMUX_READ) {
+						res = read(p->subs[index].zfd, buf, sizeof(buf));
+						if (res < 0) {
+							if (errno != ELAST) {
+								ast_log(LOG_WARNING, "read returned error: %s\n", strerror(errno));
+								callerid_free(cs);
+								ast_hangup(chan);
+								return NULL;
+							}
+							break;
+						}
+						if (p->ringt) 
+							p->ringt--;
+						if (p->ringt == 1) {
+							res = -1;
+							break;
+						}
+					}
+				}
+				if(option_verbose > 2) 
+					/* this only shows up if you have n of the dring patterns filled in */
+					ast_verbose( VERBOSE_PREFIX_3 "Detected ring pattern: %d,%d,%d\n",curRingData[0],curRingData[1],curRingData[2]);
+
+				for (counter=0; counter < 3; counter++) {
+					/* Check to see if the rings we received match any of the ones in zapata.conf for this
+					channel */
+					distMatches = 0;
+					for (counter1=0; counter1 < 3; counter1++) {
+						if (curRingData[counter1] <= (p->drings.ringnum[counter].ring[counter1]+10) && curRingData[counter1] >=
+						(p->drings.ringnum[counter].ring[counter1]-10)) {
+							distMatches++;
+						}
+					}
+					if (distMatches == 3) {
+						/* The ring matches, set the context to whatever is for distinctive ring.. */
+						strncpy(p->context, p->drings.ringContext[counter].contextData, sizeof(p->context)-1);
+						strncpy(chan->context, p->drings.ringContext[counter].contextData, sizeof(chan->context)-1);
+						if(option_verbose > 2) 
+							ast_verbose( VERBOSE_PREFIX_3  "Distinctive Ring matched context %s\n",p->context);
+						break;
+					}
+				}
+			}
+			/* Restore linear mode (if appropriate) for Caller*ID processing */
+			zt_setlinear(p->subs[index].zfd, p->subs[index].linear);
+#if 1
+			restore_gains(p);
+#endif
 		/* If we want caller id, we're in a prering state due to a polarity reversal
 		 * and we're set to use a polarity reversal to trigger the start of caller id,
 		 * grab the caller id and wait for ringing to start... */
@@ -10501,6 +10620,8 @@
 				confp->chan.cid_start = CID_START_RING;
 			else if (!strcasecmp(v->value, "polarity"))
 				confp->chan.cid_start = CID_START_POLARITY;
+			else if (!strcasecmp(v->value, "usehist"))
+				confp->chan.cid_start = CID_START_USEHIST;
 			else if (ast_true(v->value))
 				confp->chan.cid_start = CID_START_RING;
 		} else if (!strcasecmp(v->name, "threewaycalling")) {
Index: include/asterisk/callerid.h
===================================================================
--- include/asterisk/callerid.h	(revision 49783)
+++ include/asterisk/callerid.h	(working copy)
@@ -58,6 +58,7 @@
 
 #define CID_START_RING	1
 #define CID_START_POLARITY 2
+#define CID_START_USEHIST 3
 
 
 #define AST_LIN2X(a) ((codec == AST_FORMAT_ALAW) ? (AST_LIN2A(a)) : (AST_LIN2MU(a)))