<-- SIP read from 211.252.90.60:5060: 
SIP/2.0 501 Not Implemented
Via: SIP/2.0/UDP 211.222.158.114:5060;branch=z9hG4bK6280c6b6;rport
To: <sip:5124343161324114-01@211.252.90.60:5060>
From: "Private" <sip:Private@211.222.158.114>;tag=as53df1d41
Call-ID: 6191810229ac583234ecb96519efa83b@211.222.158.114
CSeq: 102 OPTIONS
User-Agent: Axon 1.09
Content-Length: 0