Grandstream BLF key's grey'd out on multiple phones.

[Justin Steen]

Hey,

I have a customer who has locations in multiple cities but I have an issue with the parking BLF keys in one city. Currently everyone in this office has their BLF keys grey'd and not lit except for two people. This happens very randomly. We tried rebooting the 3CX server and the phones. There are 20 phones in this office. 1 - 2170 and 19 -1760s. The 2170 currently works and 1 of the 1760s work. Most phones are on firmware version 1.0.1.74 except for the 2170 is on 1.0.9.108. Now I can factory the phone and re-provision and it will temporarily fix the problem but I suspect that won't be a permanent fix. Any ideas what might be causing this?

3CX version: 15.515502.6

 

[craigreilly]

Where is the server in relationship to the phones?

 

[Justin Steen]

The server is in the Amazon cloud.

 

[YiannisH_3CX]

Hello @Justin Steen

Are you using STUN or SBC to connect the phones to the PBX? If you are using STUN then make sure that each phone has a different SIP port assigned to it and that those ports are correctly forwarded to the local IP of the phone.
If a BLF key is greyed out it could suggest that the subscription to the BLF has failed. Do you have any other issues with the phones?

 

[Justin Steen]

We always use different SIP ports for different extensions and yes its on STUN. BLF issues seems to be the only issue with this customer.

 

[JohnS_3CX]

Hi Justin,

The office site firewall needs to be configured correctly with SIP-ALG disabled, and with port forwards set for each and every phone (SIP and RTP ranges) to ensure that everything works smoothly.

Generally speaking, if you have 20 phones in the office and you face such intermittent problems you may benefit from installing an SBC rather than keeping them all on STUN which should make life a little easier from a network management and troubleshooting perspective.

 

[Justin Steen]

Yeah we have the firewall set up correctly. Using a Cisco Meraki. I'll inquire if a SBC make sense.