Unable to register IP phones or making calls on linkus will show registering in some countries



In some Middle East countries like Egypt, Bahrain, Qatar, Oman, UAE and Pakistan (even RTP is blocked), sip protocol (UDP 5060) is blocked by the ISP. This leads to failure in registering IP phones or linkus to LCS Pro server remotely.




IP Phone:

Using the TLS protocol without certificates


Step 1. Enable TLS in General-> SIP->TLS on the PBX, and restart the PBX.


S series PBX:


P series PBX:


Step 2. Enable Register Remotely on Advanced in the extension settings and select the TLS protocol.


S series PBX



P series PBX:


Step 3. Use the LCS Pro FQDN and TLS/ port 5061 to register the phone.



Step 4. Disable the 'only accept trusted certificates' option on the phone. Otherwise, it will fail to register.

1)  Disabled the option of Only Accept Trusted Certificates.

2)  Disabled the option of Common Name Validation.

3)  Choose All Certificates as the CA Certificates.





After completing step 2 above, log out of the linkus and log in to the linkus again and it will register with the TLS protocol.


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  • 0

    Its working but after sometime I am getting 603 and 488 error


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