[SR-Users] sipp dead calls

Hi guys, We are testing kamailio with sipp. We are running it with 20cps and some calls do the following. When Kamailio is processing the 'ringing' a '200ok' arrives in the middle. First, kamailio forwards the 200 ok and then the ringing. 'ACK' arrives and, I suppose, the call is established. The thing is than when the 'BYE' arrives kamailio responds with a 404. This is the summary of the call Id Time Source Destination Protocol Len Info 6483 2016-12-14 11:26:06.264697 SIPP-A KAMAILIO SIP/SDP 692 Request: INVITE sip:11111111@172.16.213.38:5060 | 6484 2016-12-14 11:26:06.264937 KAMAILIO SIPP-A SIP 367 Status: 100 trying -- your call is important to us | 6485 2016-12-14 11:26:06.266327 KAMAILIO SIPP-B SIP/SDP 1179 Request: INVITE sip:22222222@172.16.213.31:5060 | *6486 2016-12-14 11:26:06.267217 SIPP-B KAMAILIO SIP 566 Status: 180 Ringing | * 6487 2016-12-14 11:26:06.267268 SIPP-B KAMAILIO SIP/SDP 733 Status: 200 OK | 6488 2016-12-14 11:26:06.267758 KAMAILIO SIPP-A SIP/SDP 788 Status: 200 OK | *6489 2016-12-14 11:26:06.267833 *KAMAILIO SIPP-A* SIP 442 Status: 180 Ringing | * 6490 2016-12-14 11:26:06.268868 SIPP-A KAMAILIO SIP 493 Request: ACK sip:127.0.0.8;line=sr-N6IAzBFwMJZfWJZLM.M7MlF-W.y6Mx14NEt7Nw05NhPQKjaP | 6491 2016-12-14 11:26:06.269162 KAMAILIO SIPP-B SIP 609 Request: ACK sip:172.16.213.31:5060;transport=UDP | 6492 2016-12-14 11:26:06.269614 SIPP-A KAMAILIO SIP 404 Request: BYE sip:11111111@172.16.213.38:5060 | 6493 2016-12-14 11:26:06.269782 KAMAILIO SIPP-A SIP 348 Status: *404 Not here* | We are using modules rtjson, evapi, uac, topoh, rtpproxy for all calls. My debug level is -1. With higher levels this behavior increase. Kamailio is running in a virtual machine with centos7 with 8 cores and 8gb of ram. Do you need any further information? I can send you a pcap or ngrep file. Best regards, Diego.