--- ./include/asterisk/res_pjsip.h.orig	2017-03-11 15:06:03.813529700 +1100
+++ ./include/asterisk/res_pjsip.h	2017-03-11 15:23:02.152125570 +1100
@@ -755,6 +755,8 @@
 	char *contact_user;
 	/*! Do we allow an asymmetric RTP codec? */
 	unsigned int asymmetric_rtp_codec;
+	/*! Do we allow overlap dialling? */
+	unsigned int allow_overlap;
 };
 
 /*!
--- ./res/res_pjsip/pjsip_configuration.c.orig	2017-03-11 14:20:05.301720984 +1100
+++ ./res/res_pjsip/pjsip_configuration.c	2017-03-11 15:22:26.817306635 +1100
@@ -1938,6 +1938,7 @@
 	ast_sorcery_object_field_register(sip_sorcery, "endpoint", "subscribe_context", "", OPT_CHAR_ARRAY_T, 0, CHARFLDSET(struct ast_sip_endpoint, subscription.context));
 	ast_sorcery_object_field_register_custom(sip_sorcery, "endpoint", "contact_user", "", contact_user_handler, contact_user_to_str, NULL, 0, 0);
 	ast_sorcery_object_field_register(sip_sorcery, "endpoint", "asymmetric_rtp_codec", "no", OPT_BOOL_T, 1, FLDSET(struct ast_sip_endpoint, asymmetric_rtp_codec));
+	ast_sorcery_object_field_register(sip_sorcery, "endpoint", "allow_overlap", "no", OPT_BOOL_T, 1, FLDSET(struct ast_sip_endpoint, allow_overlap));
 
 	if (ast_sip_initialize_sorcery_transport()) {
 		ast_log(LOG_ERROR, "Failed to register SIP transport support with sorcery\n");
--- ./res/res_pjsip.c.orig	2017-03-11 14:20:34.340395292 +1100
+++ ./res/res_pjsip.c	2017-03-11 15:22:09.346901444 +1100
@@ -100,6 +100,9 @@
 				<configOption name="allow">
 					<synopsis>Media Codec(s) to allow</synopsis>
 				</configOption>
+				<configOption name="allow_overlap" default="no">
+					<synopsis>Allow support for SIP overlap dialling</synopsis>
+				</configOption>
 				<configOption name="aors">
 					<synopsis>AoR(s) to be used with the endpoint</synopsis>
 					<description><para>
@@ -2057,6 +2060,9 @@
 				<parameter name="SubscribeContext">
 					<para><xi:include xpointer="xpointer(/docs/configInfo[@name='res_pjsip']/configFile[@name='pjsip.conf']/configObject[@name='endpoint']/configOption[@name='subscribe_context']/synopsis/node())"/></para>
 				</parameter>
+				<parameter name="Allowoverlap">
+					<para><xi:include xpointer="xpointer(/docs/configInfo[@name='res_pjsip']/configFile[@name='pjsip.conf']/configObject[@name='endpoint']/configOption[@name='allow_overlap']/synopsis/node())"/></para>
+				</parameter>
 			</syntax>
 		</managerEventInstance>
 	</managerEvent>
--- ./res/res_pjsip_session.c.orig	2017-03-11 11:57:10.060157790 +1100
+++ ./res/res_pjsip_session.c	2017-03-11 15:22:45.753745705 +1100
@@ -2006,10 +2006,17 @@
 
 		return SIP_GET_DEST_EXTEN_FOUND;
 	}
-	/* XXX In reality, we'll likely have further options so that partial matches
-	 * can be indicated here, but for getting something up and running, we're going
-	 * to return a "not exists" error here.
-	 */
+
+	/*
+	 * Check for partial match via overlap dialling (if enabled)
+         */
+	if (session->endpoint->allow_overlap && (
+		!strncmp(session->exten, pickupexten, strlen(session->exten)) ||
+		ast_canmatch_extension(NULL, session->endpoint->context, session->exten, 1, NULL))) {
+		/* Overlap partial match */
+		return SIP_GET_DEST_EXTEN_PARTIAL;
+	}
+
 	return SIP_GET_DEST_EXTEN_NOT_FOUND;
 }
 
@@ -2126,8 +2133,17 @@
 			pjsip_inv_terminate(invite->session->inv_session, 416, PJ_TRUE);
 		}
 		goto end;
-	case SIP_GET_DEST_EXTEN_NOT_FOUND:
 	case SIP_GET_DEST_EXTEN_PARTIAL:
+		ast_debug(1, "Call from '%s' (%s:%s:%d) to extension '%s' - partial match\n", ast_sorcery_object_get_id(invite->session->endpoint),
+			invite->rdata->tp_info.transport->type_name, invite->rdata->pkt_info.src_name, invite->rdata->pkt_info.src_port, invite->session->exten);
+
+		if (pjsip_inv_initial_answer(invite->session->inv_session, invite->rdata, 484, NULL, NULL, &tdata) == PJ_SUCCESS) {
+			ast_sip_session_send_response(invite->session, tdata);
+		} else  {
+			pjsip_inv_terminate(invite->session->inv_session, 484, PJ_TRUE);
+		}
+		goto end;
+	case SIP_GET_DEST_EXTEN_NOT_FOUND:
 	default:
 		ast_log(LOG_NOTICE, "Call from '%s' (%s:%s:%d) to extension '%s' rejected because extension not found in context '%s'.\n",
 			ast_sorcery_object_get_id(invite->session->endpoint), invite->rdata->tp_info.transport->type_name, invite->rdata->pkt_info.src_name,