commit b1b410469362860daac798af5a90d7334a1c975a
Author: Moises Silva <moises.silva@gmail.com>
Date:   Thu Oct 13 03:06:56 2016 -0400

    chan_rtp: Set a sane default rtp engine for unicast.
    
    ASTERISK-26439
    
    Change-Id: I7f5ee2eeba8906e9ecb3293dbe3a747770bb5011

diff --git a/channels/chan_rtp.c b/channels/chan_rtp.c
index 0fe66bd..f1f4f05 100644
--- a/channels/chan_rtp.c
+++ b/channels/chan_rtp.c
@@ -314,7 +314,7 @@ static struct ast_channel *unicast_rtp_request(const char *type, struct ast_form
 	}
 
 	engine_name = S_COR(ast_test_flag(&opts, OPT_RTP_ENGINE),
-		opt_args[OPT_ARG_RTP_ENGINE], NULL);
+		opt_args[OPT_ARG_RTP_ENGINE], "asterisk");
 
 	ast_ouraddrfor(&address, &local_address);
 	instance = ast_rtp_instance_new(engine_name, NULL, &local_address, NULL);