Someone

U 64.26.157.252:5060 -> 207.xxx.yyy.37:5060
INVITE sip:8665464848@207.xxx.yyy.37;user=phone SIP/2.0.
Via: SIP/2.0/UDP 64.26.157.252:5060;branch=z9hG4bK3805102246.
From: <sip:5192915112@64.26.157.252;user=phone>;tag=89188638-e65d776e.
To: <sip:8665464848@207.xxx.yyy.37;user=phone>.
Call-ID: 867a472b-89188638-c8e11ba0-e65d776e@64.26.157.252.
CSeq: 1001 INVITE.
Contact: <sip:5192915112@64.26.157.252;user=phone>.
Max-Forwards: 70.
User-Agent: Tangerine-oSIP-UA/1.06.
Allow: INVITE, ACK, CANCEL, BYE.
Content-Type: application/sdp.
Content-Length:   217.
.
v=0.
o=VOIPSIL_SIP 1565071079 1565071079 IN IP4 64.26.157.252.
s=Sip Call.
c=IN IP4 64.26.157.226.
t=0 0.
m=audio 6428 RTP/AVP 18 0 101.
a=rtpmap:18 G729/8000.
a=rtpmap:0 PCMU/8000.
a=rtpmap:101 telephone-event/8000.

#
U 207.xxx.yyy.37:5060 -> 64.26.157.252:5060
SIP/2.0 404 Not Found.
Via: SIP/2.0/UDP 64.26.157.252:5060;branch=z9hG4bK3805102246;received=64.26.157.252.
From: <sip:5192915112@64.26.157.252;user=phone>;tag=89188638-e65d776e.
To: <sip:8665464848@207.xxx.yyy.37;user=phone>;tag=as287d18c9.
Call-ID: 867a472b-89188638-c8e11ba0-e65d776e@64.26.157.252.
CSeq: 1001 INVITE.
User-Agent: Asterisk PBX.
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY.
Supported: replaces.
Content-Length: 0.