Loop Detected

As per the relevant RFC (3261):

21.4.20 482 Loop Detected

The server has detected a loop (Section 16.3 Item 4).

4 Optional Loop Detection check

  An element MAY check for forwarding loops before forwarding a
  request.  If the request contains a Via header field with a sent-
  by value that equals a value placed into previous requests by the
  proxy, the request has been forwarded by this element before.  The
  request has either looped or is legitimately spiraling through the
  element.  To determine if the request has looped, the element MAY
  perform the branch parameter calculation described in Step 8 of
  Section 16.6 on this message and compare it to the parameter
  received in that Via header field.  If the parameters match, the
  request has looped.  If they differ, the request is spiraling, and
  processing continues.  If a loop is detected, the element MAY
  return a 482 (Loop Detected) response.

Presumably your comment meant to show this:

REGISTER sip:188.247.67.90;transport=UDP SIP/2.0
Via: SIP/2.0/UDP 10.179.128.228:49012;branch=z9hG4bK-524287-1---3d15be2bf3d75655;rport
Max-Forwards: 70
Contact: sip:[email protected]:49012;rinstance=24fc7df247922ed7;transport=UDP
To: "203"sip:[email protected];transport=UDP
From: "203"sip:[email protected];transport=UDP;tag=88f9ff4d
Call-ID: 9M-KyvmjzBrGB4TqI3H5Fg..
CSeq: 1 REGISTER
Expires: 60
Allow: INVITE, ACK, CANCEL, BYE, NOTIFY, REFER, MESSAGE, OPTIONS, INFO, SUBSCRIBE
Supported: replaces, norefersub, extended-refer, timer, outbound, path, X-cisco-serviceuri
User-Agent: Zoiper r30911
Allow-Events: presence, kpml
Content-Length: 0
SIP/2.0 482 Loop Detected
Via: SIP/2.0/UDP 10.179.128.228:49012;branch=z9hG4bK-524287-1—3d15be2bf3d75655;received=188.247.77.83;rport=33785
From: "203"sip:[email protected];transport=UDP;tag=88f9ff4d
Call-ID: 9M-KyvmjzBrGB4TqI3H5Fg..
CSeq: 1 REGISTER
To: "203"sip:[email protected];transport=UDP;tag=488579bf366f69151236
Server: SIParator/5.0.5
Content-Length: 0

Are those the contents of the same capture file you showed a screenshot of?

It doesn’t look like it would be the same messages, but if it is that’s even more confusing… because the IP layer shown in the screenshot showed the IP source address of 188.247.67.90 and destination address of 192.168.0.113 (in the third and fourth columns). Or are your columns reversed? What exactly are the IP source and destination addresses of the SIP message contents shown above (not the SIP-layer info, but the IP-layer info).

I was assuming the IP source was 188.247.67.90, sending a SIP REGISTER request message to 192.168.0.113, but with a SIP request URI of “sip:188.247.67.90;transport=tcp”. That would cause a loop, because when the SIP device on 192.168.0.113 receives it, it will want to forward it right back to 188.247.67.90 (although it may not be a loop if it forwards it to a different TCP/UDP port, but I’ll ignore that detail for now).

The “To” and the “From” headers don’t actually decide how SIP messages are “routed” at the SIP layer (despite the words “To” and “From” sounding like they should). For SIP request messages, such as the REGISTER request, the “request URI” is what decides the ultimate target (along with any “Route” headers, but you don’t have those). The request URI is the string “sip:188.247.67.90;transport=UDP” right after the word “REGISTER”, the first line of the SIP message. The “To” header URI in a REGISTER request identifies the address-of-record being registered for, and the “From” header URI in a REGISTER request identifies the entity performing the registration - usually the same as the “To” header URI, except for third-party registrations (which does not apply to your case).

I don’t know the inGate Siparator, but presumably it’s a SIP ALG, such that it will replace various SIP headers to make it work though NATs and hide internal addressing. So to figure out what’s going wrong we might need a capture of both the “inside” and “outside” packets - i.e., the ones sent to/from the Zoiper soft phone to the inGate, and the ones sent to/from the inGate and the SIP service provider.

But as I said before, you probably didn’t configure your SIP phone correctly (the Zoiper softphone). For a Zoiper, there’s a “Account Wizard” dialog box that shows up when you create the SIP account - what did you set the “[email protected]” field and “domain/outbound proxy” fields to? My guess is one of those two is not set correctly. It looks like you set one of them to “188.247.67.90”, when it should instead be the domain name of your SIP service provider.