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Category: SIP UA

Problem with a VoIP phone behind NAT – disabling FortiGate SIP ALG

Initial state and observed problems

Observed problems

We had observed a problem, where a SIP phone is registering, but the AOR record indicates, that as a Contact IP address the incorrect and strange private IP address is used. As is shown on following listing:

voip*CLI> pjsip show aor 1765
   Aor:  <Aor..............................................>  <MaxContact>
   Aor:  1765                                                 1 Contact:  1765/sip:1765@              f123d14d1c NonQual         nan
 ParameterName        : ParameterValue
  authenticate_qualify : false
  contact              : sip:1765@
  default_expiration   : 7200
  mailboxes            :
  max_contacts         : 1
  maximum_expiration   : 7200
  minimum_expiration   : 60
  outbound_proxy       :
  qualify_frequency    : 0
  qualify_timeout      : 3.000000
  remove_existing      : true
  support_path         : false
  voicemail_extension  :

This cause a problem, where incoming phone calls (call on 1765 number) are not reaching the SIP phone. We had tried to solve the situations on the phone only modifying its NAT configuration and using STUN, but with no success. Then we setup the lab with two Cisco NAT to simulate the topo. It works perfectly. This indicate on a problem with the Fortigate firewall. Several posts indicates that it could be the SIP ALG problem, which is on Fortigate devices turned on by default and it modifies SIP messages.

Configuring IMS Boghe to use SIP over IPv6 for an IETF SIP network

After some testing I have found another SIP client, which shoud be used for SIP over IPv6 testing. The first one is Linhpone and the second one is IMS Boghe client. Right, Boghe is mainly IMS client, but may be used as an IETF SIP client, which allows to register and use an IETF SIP based network.

To make it working using IPv6 you have to change the following. Start the client and from the main menu choose Tools and Options.