MPK Keys Not Working


We have had issues over the last few weeks with our phones. The BLF keys do not light up and nothing happens when we press the button. We are able to dial numbers, extensions, and receive calls. This is affecting GXP2160 and GXP2130 models. The issue is affecting 3 different sites, each with their own firewall (Fortinet and Sonicwall). We have had the phones for 2.5 years and it is just now an issue. Firmware is on and and previous versions. No firewall changes have been made recently for 2 of the sites.


@MIT what IP PBX are you using and is it on prem or is it off-site? If off-site, how do the phones connect to the IP PBX?


We use Cytracom, a hosted VOIP solution. As for how it connects, I’m not entirely sure what you mean.


I mean how do the phones connect to the SIP server? Is there an SBC? Do you use Stun? Etc.

So you are using a cloud hosted PBX. Did they make any changes? How did they provision the phones? Have you reached out to their tech support with respect to this problem?

I suspect you are going to need to generate some packet captures and have them examined by someone who knows how to read them (this unfortunately is not one of my skills).

I suggest you open a ticket with Grandstream Tech Support


And is it just now an issue after updating the firmware? If you reboot a phone, do the MPK start back up? Have you added any extensions to the site recently? Is it all phones or only some? Something, somewhere, somehow has changed. What might have changed as you have to consider all aspects that come into play.


Hello Mr. Benjamin,
I think the problem is in the cytracom’s configuration. Please see the link below (Disable Active MPK) :

or you can see cytracom’s user manual or you can contact cytracom’s team support, I hope they can help you

Best Regards,

Raymond Sahertian