U X.X.X.X:5060 -> Y.Y.Y.Y:5060
ACK sip:Y.Y.Y.Y:5060;transport=udp SIP/2.0.
Via: SIP/2.0/UDP X.X.X.X;branch=z9hG4bKcydzigwkX.
Via: SIP/2.0/UDP Z.Z.Z.Z:5060;branch=z9hG4bK077293e0;rport=5060.
From: "1111" <sip:1111@Z.Z.Z.Z>;tag=as35541df8.
To: <sip:011919986013142@X.X.X.X>;tag=52BBDC4F-18FAC498-AC1C1B69.
Contact: <sip:1111@Z.Z.Z.Z>.
Call-ID: 051f04c861941212308149bf3e7e4ea0@Z.Z.Z.Z.
CSeq: 102 ACK.
User-Agent: Switch.
Max-Forwards: 69.
Content-Length: 0.
.
U X.X.X.X:5060 -> Y.Y.Y.Y:5060
ACK sip:Y.Y.Y.Y:5060;transport=udp SIP/2.0.
Via: SIP/2.0/UDP X.X.X.X;branch=z9hG4bKcydzigwkX.
Via: SIP/2.0/UDP Z.Z.Z.Z:5060;branch=z9hG4bK577c532e;rport=5060.
From: "801555555555" <sip:801555555555@Z.Z.Z.Z>;tag=as706a0ac1.
To: <sip:011919916731781@X.X.X.X>;tag=52BBDC34-18FABB83-AC1C1B69.
Contact: <sip:801555555555@Z.Z.Z.Z>.
Call-ID: 5a795f6a1c76095a515a22fd356526ea@Z.Z.Z.Z.
CSeq: 102 ACK.
User-Agent: Switch.
Max-Forwards: 69.
Content-Length: 0.