CANCEL request from Android SIP demo ignored by Asterisk 1.8

I had a strange problem when using the standard Android SIP Demo in combination with asterisk 1.8.9.2 server: incoming / outgoing calls work correctly, but there is one thing that does not work: when I start a call from SIP demo and I close the call again ( by clicking the “End Current Call” button), the call ends in the SIP demo, but the called device still continues to ring.

I tried to check what happens by registering telegrams through Wireshark, and it seems that the CANCEL telegram from the SIP demonstration to the asterisk server is not received, look:

300 08:30:39.483913 130.10.0.102    192.168.0.110   SIP/SDP 916 Request: INVITE sip:110@192.168.0.110:5060, with session description
301 08:30:39.488686 192.168.0.110   130.10.0.102    SIP 525 Status: 100 Trying
302 08:30:39.524884 192.168.0.110   130.10.0.102    SIP 541 Status: 180 Ringing
309 08:30:41.041071 130.10.0.102    192.168.0.110   SIP 370 Request: CANCEL sip:110@192.168.0.110:5060
310 08:30:41.051545 192.168.0.110   130.10.0.102    SIP 526 Status: 481 Call/Transaction Does Not Exist

And now the real strange thing: if I repeat the same action, and until the call is completed through the "End Current Call" button, I wait approx. 7 seconds, CANCEL is accepted and the call ends correctly:

646 08:31:05.571464 130.10.0.102    192.168.0.110   SIP/SDP 916 Request: INVITE sip:110@192.168.0.110:5060, with session description
647 08:31:05.576150 192.168.0.110   130.10.0.102    SIP 525 Status: 100 Trying
648 08:31:05.662345 192.168.0.110   130.10.0.102    SIP 541 Status: 180 Ringing
664 08:31:08.302561 130.10.0.102    192.168.0.110   SIP 389 Request: OPTIONS sip:192.168.0.110
665 08:31:08.312097 192.168.0.110   130.10.0.102    SIP 528 Status: 404 Not Found
698 08:31:13.370346 130.10.0.102    192.168.0.110   SIP 370 Request: CANCEL sip:110@192.168.0.110:5060
699 08:31:13.373570 192.168.0.110   130.10.0.102    SIP 513 Status: 487 Request Terminated
700 08:31:13.373912 192.168.0.110   130.10.0.102    SIP 497 Status: 200 OK

I checked the contents of both CANCEL requests and the structure is completely the same! In addition, I also tested the server with an asterisk 1.6, and there I did NOT encounter this problem, the call ended correctly there! Therefore, it seems to me that he should do something with an asterisk. 1.8.

Has anyone encountered similar issues and had some helpful tips for me? If additional data is needed for analysis, just let me know! Thanks for your help, BR

Armin