diff --git a/README.md b/README.md
index aaee16548..abcf6d891 100644
--- a/README.md
+++ b/README.md
@@ -829,6 +829,14 @@ Optionally included keys are:
 
 	Valid values are: `RTP/AVP`, `RTP/AVPF`, `RTP/SAVP`, `RTP/SAVPF`.
 
+	Additionally the string `accept` can be given in `answer` messages to allow a special case: By
+	default (when no `transport-protocol` override is given) in answer messages, *rtpengine* will
+	use the transport protocol that was originally offered. However, an answering client may answer
+	with a different protocol than what was offered (e.g. offer was for `RTP/AVP` and answer comes
+	with `RTP/AVPF`). The default behaviour for *rtpengine* is to ignore this protocol change and
+	still proceed with the protocol that was originally offered. Using the `accept` option here
+	tells *rtpengine* to go along with this protocol change and pass it to the original offerer.
+
 * `media address`
 
 	This can be used to override both the addresses present in the SDP body
diff --git a/daemon/call.c b/daemon/call.c
index 9a2071a7f..5e8ddc4d7 100644
--- a/daemon/call.c
+++ b/daemon/call.c
@@ -1878,14 +1878,30 @@ static void __update_media_protocol(struct call_media *media, struct call_media
 	/* deduct protocol from stream parameters received */
 	if (other_media->protocol != sp->protocol) {
 		other_media->protocol = sp->protocol;
-		/* if the endpoint changes the protocol, we reset the other side's
+		/* If the endpoint changes the protocol, we reset the other side's
 		 * protocol as well. this lets us remember our previous overrides,
 		 * but also lets endpoints re-negotiate.
-		 * Exception: OSRTP answer/accept. */
-		if (flags && flags->opmode == OP_ANSWER && other_media->protocol && other_media->protocol->rtp
-				&& !other_media->protocol->srtp
-				&& media->protocol && media->protocol->osrtp && flags->osrtp_accept)
-			;
+		 * Answers are a special case: handle OSRTP answer/accept, but otherwise
+		 * answer with the same protocol that was offered, unless we're instructed
+		 * not to. */
+		if (flags && flags->opmode == OP_ANSWER) {
+			// OSRTP?
+			if (other_media->protocol && other_media->protocol->rtp
+					&& !other_media->protocol->srtp
+					&& media->protocol && media->protocol->osrtp)
+			{
+				// accept it?
+				if (flags->osrtp_accept)
+					;
+				else
+					media->protocol = NULL; // reject
+			}
+			// pass through any other protocol change?
+			else if (!flags->protocol_accept)
+				;
+			else
+				media->protocol = NULL;
+		}
 		else
 			media->protocol = NULL;
 	}
diff --git a/daemon/call_interfaces.c b/daemon/call_interfaces.c
index 330550c2a..f3f0a8810 100644
--- a/daemon/call_interfaces.c
+++ b/daemon/call_interfaces.c
@@ -931,8 +931,13 @@ static void call_ng_process_flags(struct sdp_ng_flags *out, bencode_item_t *inpu
 	call_ng_flags_list(out, input, "T.38", ng_t38_option, NULL);
 #endif
 
-	bencode_get_alt(input, "transport-protocol", "transport protocol", &out->transport_protocol_str);
-	out->transport_protocol = transport_protocol(&out->transport_protocol_str);
+	str transport_protocol_str;
+	bencode_get_alt(input, "transport-protocol", "transport protocol", &transport_protocol_str);
+	if (!str_cmp(&transport_protocol_str, "accept"))
+		out->protocol_accept = 1;
+	else
+		out->transport_protocol = transport_protocol(&transport_protocol_str);
+
 	bencode_get_alt(input, "media-address", "media address", &out->media_address);
 	if (bencode_get_alt(input, "address-family", "address family", &out->address_family_str))
 		out->address_family = get_socket_family_rfc(&out->address_family_str);
diff --git a/include/call_interfaces.h b/include/call_interfaces.h
index b8d772175..26b84802e 100644
--- a/include/call_interfaces.h
+++ b/include/call_interfaces.h
@@ -25,7 +25,6 @@ struct sdp_ng_flags {
 	str received_from_family;
 	str received_from_address;
 	str media_address;
-	str transport_protocol_str;
 	str address_family_str;
 	const struct transport_protocol *transport_protocol;
 	sockaddr_t parsed_received_from;
@@ -47,6 +46,7 @@ struct sdp_ng_flags {
 	    rev_ptime;
 	GHashTable *sdes_no;
 	int asymmetric:1,
+	    protocol_accept:1,
 	    no_redis_update:1,
 	    unidirectional:1,
 	    trust_address:1,