PC - PC no problem.
Problem with FXS Adapter (DNS not find name computer).
I'm have FXS - 101@192.168.0.101 and Axon PBX - 192.168.0.11 on computer with name 'tailor'
First INVITE - send sip:106@192.168.0.11
Next INVITE (post REFER) - send sip:101@tailor - 
FXS (D-link-4022S) send '486 Busy Here'.
14:37:32 UDP Packet Sent to 192.168.0.101:5060 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
INVITE sip:101@192.168.0.101:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.0.11:5060;rport;branch=z9hG4bK181280
To: <sip:101@tailor>
From: "Vadim" <sip:106@192.168.0.11>;tag=6632
Call-ID: 1150453613-1280-TAILOR@192.168.0.11
CSeq: 189 INVITE
Max-Forwards: 20
User-Agent: Axon 1.07
Contact: <sip:101@192.168.0.11:5060>
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, INFO, REFER, NOTIFY
Supported: replaces
Content-Length: 0
14:37:32 UDP Packet Received from 192.168.0.101:5060 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
SIP/2.0 486 Busy Here
From: "Vadim"<sip:106@192.168.0.11>;tag=6632
To: <sip:101@tailor>
Call-ID: 1150453613-1280-TAILOR@192.168.0.11
CSeq: 189 INVITE
Via: SIP/2.0/UDP 192.168.0.11:5060;rport=5060;branch=z9hG4bK181280
Max-Forwards: 20
User-Agent: Axon 1.07
Supported: replaces
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,INFO,REFER,NOTIFY
Content-Length: 0