Checklist for SIP Extension Registration Failure


If your extension registration failed, you could check the issue by 2 sides: the PBX side and the Client side.

If you wanna get more details on SIP registration theory, you could read the basic introduction for SIP registration firstly.

I. PBX Side

Please check Extension Configurations that would be relevant with the registration issue:

Extension Configuration

1. IP Restriction : Once you enable the IP Restriction on Edit Extension page, you should remember add the IP of your phone into permitted IP address.  (go to Settings>Extensions>Edit Extension page>Advanced)

2. Concurrent Registrations: If you want to register one extension with two IP phones, it is essential to make sure the Concurrent Registration number greater than one.

3. User Agent: E.g The User Agent ‘Yealink’ restricts that only Yealink IP phone could register. Usually you could leave it blank if don’t need this restriction. 

(go to Settings>Extensions>Edit Extension page>Advanced)

4. Transport: You need to check if the type of transport on IP phone is matched with the value.

(go to Settings>Extensions>Edit Extension page>Advanced)

5. Remote Register: If you want to register an extension remotely, please check the option has been enabled.



  1. Network is reachable: Make sure the network between PBX and SIP devices is reachable. You could use the IP Ping tool to test the network connectivity.
  2. SIP port: Make sure the port has been configured correctly. (5060 is by default)
  3. NAT: When you need register a SIP device remotely, NAT should be configured.              Get more details on NAT settings.                                   


  1.  Blocked IP address: Check the SIP device has not been blocked by the blocklist of firewall.
  2.  Firewall Rules: Once you enable the option Drop all, remember add a rule for accepting the IP address of the SIP endpoint.

Ⅱ. Client side

Make sure the registration parameters filled on Client side are correctly filled on client side.

  1. Username
  2. Password
  3. Registration name
  4. Transport: Check if transport mode and port number are matched with PBX setting
  5. Firewall: Check if local firewall blocked the IP address of PBX or phone.


If the solution above can’t help resolve your issue, you could contact us. Please describe your issue, then provide more details as the following clue to us for further analysis.
1. Screenshots of the Network Basic setting and NAT setting on PBX web GUI.
2. PCAP dump capture. 
3. Asterisk CLI Log. 

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