Dial with moh stopped too soon

I am dialing to an external voip provider (sip) with option “m”. But the MOH stopped before the called partry answers the call. I hear complete silence until the called party answers. below is the log:

-- Executing [21189100@incoming:1] Wait("SIP/", "1") in new stack
-- Executing [21189100@incoming:2] Answer("SIP/", "") i                                    n new stack
-- Executing [21189100@incoming:3] Dial("SIP/", "SIP/                              297270519@||m") in new stack
-- Called 297270519@
-- Started music on hold, class 'default', on SIP/
-- Call on SIP/ left from hold
-- Stopped music on hold on SIP/
-- SIP/ is making progress passing it to SIP/192.168.1.                                    19-0856ebe8
-- Call on SIP/ left from hold
-- SIP/ answered SIP/
-- Packet2Packet bridging SIP/ and SIP/                                    04730

pls kindly advise.