No.     Time        Source                Destination           Protocol Info
   1080 19.386658   192.168.1.15          192.168.1.10          SIP      Request: ACK sip:+41215501111@192.168.1.10

Frame 1080 (573 bytes on wire, 573 bytes captured)
Linux cooked capture
Internet Protocol, Src: 192.168.1.15 (192.168.1.15), Dst: 192.168.1.10 (192.168.1.10)
User Datagram Protocol, Src Port: sip (5060), Dst Port: sip (5060)
Session Initiation Protocol
    Request-Line: ACK sip:+41215501111@192.168.1.10 SIP/2.0
    Message Header
        Via: SIP/2.0/UDP 192.168.1.15;branch=z9hG4bK6008414cefae770f
        Via: SIP/2.0/UDP 192.168.1.11;branch=z9hG4bK6008414cefae770f
        From: <sip:+41215509999@192.168.1.15>;tag=82109cffc4d06068
        To: <sip:+41215501111@192.168.1.15>;tag=b46457f322c1e961
        Contact: <sip:+41215509999@192.168.1.11>
        Call-ID: d0f0a4e0cfa0590b@192.168.1.11
        CSeq: 50933 ACK
        User-Agent: Grandstream BT110 1.0.8.33
        Max-Forwards: 70
        Allow: INVITE,ACK,CANCEL,BYE,NOTIFY,REFER,OPTIONS,INFO,SUBSCRIBE
        Content-Length: 0