LANCOM Support Knowledgebase Document No. 1809.1116.5621.RHOO - V2.70

Troubleshooting guide: A configured SIP line cannot register with the provider


Description:
This troubleshooting guide demonstrates the options available when a configured SIP line cannot register with the provider.



Procedures:

1) Can the DNS address of the registrar be resolved?

If the DNS settings are not configured correctly in your LANCOM router, the router will not be able to correctly resolve the DNS address of the SIP registrar (e.g. tel.t-online.de).
  • In this case you should check the DNS settings of your LANCOM router in the menu IPv4 -> DNS. If DNS requests are explicitly forwarded to specific remote sites, you should check that the Forwarding settings are configured correctly.

    Information on how to configure DNS forwarding is available in this Knowledge Base document Database 'SP Knowledgebase', View '03. Edit Documents\All Documents', Document 'How do I configure DNS forwarding for IPv4 and/or IPv6 on a LANCOM router?'.

    Note:
    The Voice Call Manager has its own DNS resolver. This ensures that the correct Internet site is used for DNS resolution depending on the routing tag used. If forwarding is specified in the menu IPv4 -> DNS, the DNS resolution of the Voice Call Manager will override this.



The following traces can be helpful for troubleshooting:
  • VCM-DNS
  • DNS

How you generate trace output with LANconfig is described in this Knowledge Base document: Database 'SP Knowledgebase', View '03. Edit Documents\All Documents', Document 'Creating trace output with LANconfig'





2) Is the correct Internet connection being used for SIP line registration?

If you have configured multiple Internet connections and your VoIP line requires the use of an Internet connection belonging to the provider, you should check that you are using the correct Internet connection.

  • Check the routing table to see which routing tag is used by the provider’s Internet connection (in the menu IP Router -> Routing -> IPv4 routing table).
  • The identical routing tag has to be entered in the SIP-line configuration (in the menu Voice Call Manager -> Lines -> SIP lines on the Advanced tab).


The following traces can be helpful for troubleshooting:
  • SIP-Packet
  • Call-Manager




3) Are you using the correct access credentials?
  • Check the SIP line configuration (Menu Voice Call Manager -> Lines -> SIP lines) to see whether you are using the correct provider and authentication data.



The following traces can be helpful for troubleshooting: