[Freeswitch-users] Empty SDP in 200 OK on received re-invite while faxing with T.38

Hi all, I found that some of my faxes failed to be sent/received bcz remote PBX drop the calls after my FreeSWITCH send empty (without SDP) 200 OK message on received re-invite from remote party while sending or receiving fax with T.38. CLIENT > INVITE (G.711) > FS FS > 200 OK > CLIENT CLIENT > INVITE (T.38) > FS FS > 200 OK > CLEINT ... now receiving fax while fax is received, client send me reinvite with the same SDP T.38 details as in initial T.38 INVITE message. usually it happens after 900 or 1800 seconds - probably it kind of keepalive... FS > 200 OK (with no SDP) > CLEINT now call is dropped( freeswitch: Version 1.5.15b git 3d64402 2015-03-21 19:55:21Z 64bit centos 6 x64 any ideas?