Index: channels/chan_sip.c
===================================================================
+++ a/channels/chan_sip.c	2012-10-09 18:23:02.352742394 +0300
--- b/channels/chan_sip.c	2012-10-09 18:43:00.100741597 +0300
***************
*** 22089,22095 ****
  
  	if (p->lastinvite) {
  		/* if this is a request in an active dialog, just confirm that the dialog exists. */
! 		transmit_response_with_allow(p, "200 OK", req, 0);
  		return 0;
  	}
  
--- 22089,22095 ----
  
  	if (p->lastinvite) {
  		/* if this is a request in an active dialog, just confirm that the dialog exists. */
! 		res = transmit_response_with_sdp(p, "200 OK", req, XMIT_UNRELIABLE, FALSE, TRUE);
  		return 0;
  	}
  
***************
*** 22140,22147 ****
  			break;
  		}
  	}
! 	transmit_response_with_allow(p, msg, req, 0);
! 
  	/* Destroy if this OPTIONS was the opening request, but not if
  	   it's in the middle of a normal call flow. */
  	sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
--- 22140,22146 ----
  			break;
  		}
  	}
! 	res = transmit_response_with_sdp(p, "200 OK", req, XMIT_UNRELIABLE, FALSE, TRUE);
  	/* Destroy if this OPTIONS was the opening request, but not if
  	   it's in the middle of a normal call flow. */
  	sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);