[Serusers] Missing ACK and BYE in SIP communication.

Hi, I have a short question about ACK. Im my case it is not sent from callking side (X-lite). Why is it like that? How does Xlite know, not to send ACK? And why there is no BYE? See flow above. Flow: No. Time Source Destination Protocol Info 45 6.979169 137.138.137.166 192.168.2.2 SIP/SDP Request: INVITE sip:6891@wilanowska.homeip.net, with session description 46 6.979736 192.168.2.2 137.138.137.166 SIP Status: 100 trying -- your call is important to us 47 6.979950 192.168.2.2 81.18.210.159 SIP/SDP Request: INVITE sip:6891@81.18.210.159:10020;rinstance=18352dcff8f568bc, with session description 51 7.241103 192.168.2.2 81.18.210.159 SIP/SDP Request: INVITE sip:6891@81.18.210.159:10020;rinstance=18352dcff8f568bc, with session description 52 7.286054 81.18.210.159 192.168.2.2 SIP Status: 180 Ringing 53 7.286401 192.168.2.2 137.138.137.166 SIP Status: 180 Ringing 54 7.320840 81.18.210.159 192.168.2.2 SIP Status: 180 Ringing 55 7.321229 192.168.2.2 137.138.137.166 SIP Status: 180 Ringing 102 14.357178 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 103 14.357744 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 104 14.955213 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 105 14.955567 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 109 15.960539 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 110 15.961118 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 117 17.968614 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 118 17.969011 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 135 21.982902 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 136 21.983229 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 171 25.999316 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 172 25.999641 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 193 30.018608 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 194 30.018936 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 229 34.031607 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 230 34.032134 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 251 38.053494 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 252 38.054124 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 269 42.070209 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 270 42.070736 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description 325 46.088117 81.18.210.159 192.168.2.2 SIP/SDP Status: 200 OK, with session description 326 46.088445 192.168.2.2 137.138.137.166 SIP/SDP Status: 200 OK, with session description cheers, Daniel