[Freeswitch-users] ring tone is heard for 2 sec before busy tone on Lync client

Hi, I am using freeswitch 107 on windows platform I am working for a product where lync client can call a phone registred with Lync server. When Phone is set to DND mode and lync client calls that phone,I could hear ring tone for abt 2 sec and then busy tone comes. The behvaiour should be ,only busy tone should be heard. I removed "ringback" and "ignore_early_media" from dialplan. Please find dial plan , freeswitch logs and Wireshark capture attached with this mail. From wireshark it is clear that no 180 or 183 messages are flowing.But still from FS logs it could be figure out that,FS is entering into "RINGING"  mode. Thanks, Manjiri Deshpande