Insufficient VMRS out of GXW4224


I am trying to connect a GXW4224 gatway between a UCM and 24 Code Blue IA500D emergency call stations without success so far. The problem, according to Code Blue is that the GXW does not provide enough power out to the door stations to allow them to work. :persevere:

So far Grandstream has been unable to provide me with what power output (loop current) is, but Code Blue states previous testing has found this to be a problem.

This is a new area for me, so help here would be appreciated.

  • Does anyone know what the line voltage on the GXW is?

  • Does anyone have a suggestion as to how I can boost the line voltage between these devices?

  • Although I would prefer to say with Grandstream, does anyone know of a gateway with more power I should loiok at?

  • Any other thoughts, ideas and/or suggestions?


Make sure you have the 5.0A Power supply installed. Here are the spec’s , seems to be 48V out.


Everything is plugged in via what Grandstream provides.

Well I’ve heard back from Grandstream tech support.

we use the standard 4-20 mA for current loop as it’s principal industrial standard

It seems that the device was designed to provide power based on that needed for “process control” application versus that needed for standard Bell line applications (i.e. some analogue phones).

I am very disappointed by this, especially as Grandstream does not document the current loop in ANY of its documentation (in fact sales had me open support ticket to get this).

I ran into a similar power issue with an HT801 several months ago too,


Agree couldn’t see loop current anywhere and the Code Blue seems to be a High Current device with no DC Power inputs. Put in a traditional PBX, some things work best the old way.


Thanks @Telefonix, but I have two concerns about your alternative. Firstly, I don’t sell/install/support traditional phone systems; I only do VoIP. And secondly, it wouldn’t be a Grandstream solution.

Personally, I’m just very disappointed in what I;ve found out so far regarding the power output on Grandstream FXS ports.


You can try alternative ATA ports from other suppliers while keeping a UCM as the control unit for the solution. Investigate Adtran , Neogate and Yeastar and Alco.


Thanks for the suggestion @Telefonix.

I was told by Code Blue that the Patton gateway works. However, it’s $600 more expensive than the Grandstream unit.

It’s in my boss’s and client’s hands as to how they will proceed…


Just a quick update.

Grandstream gave me a beta software which increases the power out on the FXS ports. It works in the lab.

I was also informed that they will are going to take this into consideration for any new ATA/Gateway. I would also expect that new firmwares will do what they can given the existing hardware and power supply.