Voicemail indicator across 18 to 20 phones


Someone has reached out to me to see if there is a way to get a voicemail indicator to work where his installation has 18 to 20 phones and they all want to be on a single voicemail box (think of an old analogue system where all the phones were on one phone line).

His mix of phones includes 15 WP820s, 2 GXV3240 and couple of analogue phones on an ATA.

I can’t use a single extension as the UCM limits that to a max of 10 devices, and Group Voicemail would require clearing the message from all the extensions. Furthermore, voicemail to email is out.

Can anyone think of a way to do this?


The issue is that you really need to have the extensions subscribe to a common mail box. Using the concurrent registrations (not withstanding the limits mentioned) would cause all the phones with the same extension number to all ring at the same time.

This is why most systems use a group mail system that forwards as the phones are typically only able to subscribe to extensions that are set on the device itself and the MWI is a function of the NOTIFY to the subscription when a VM is received.

I do know of one system that allows for BLF monitoring of an extension’s VM box. Whether or not the UCM will do this is an unknown and I can’t test it at the moment, but the other system of which I am referring to is Asterisk based. Here is a snip from the manual -

*98 Remote Voicemail, remote entry to the voicemail system to listen to voicemail for any extension. Requires the user to input both an extension number and the voicemail password for that extension. Can also be used as a BLF to monitor and access a shared mailbox. To create a BLF to monitor the shared mailbox 2001, you should create a BLF containing *982001.

I guess you could try it and see.

I had to take my UCM that was setup out of service as a client’s IP-Office system just failed and I needed to get him up on something quickly as they are a health care facility and I already have 3 of their other offices.


Larry as always you are a wealth of knowledge and you explain things with great clarity. Thank you!

As the indicator is the key feature here, and the WP820 does NOT have BLF capabilities, I am not sure this will help in this situation. But is it something that I will remember for future use.


For your case David, the best would be a Group voicemail that is just a forwarder.

I’ve seen this in a few systems where you have 1 voicemail extension and when a message is recorded, it is copied to each selected users’ voicemail and each one can listen/delete as they wish without interfering with others. Since the VM is in the user’s voicemail, no need for extra setup on deskphones, MWI works.

I’ll see if there’s a way to replicate this on a UCM.


David, im unsure if you are allowed to in your country, but i would get a budget Grandstream handset, open it up, find the vm light, remove the light, use a relay board as a pre switch, 5 volt should be correct, and use it to trigger another relay which connects to an external lamp to indicate the voicemail has been left.


I know its left field… but check with GS to see if they cant create it for you.


Could always get an opto coupler that could do a similar thing without altering the cct board of the handset…

Maybe GS could create a device for this purpose…


I’ve set a common mail box’s on 2170’s where i have given the the keys the following to perform the common message function and it works fine. It will be ok for the 3240’s but but can’t figure out a way for the 820’s.

300 is the operator mail box, 306 is the nurses one and everyone can monitor them.


This is how the Group Voicemail box works. But in this case, as there are only two users and they only want 1 voicemail box to work with, it is impractical.


Interesting idea but I’m not sure it would be practical given the number of places the MWI would need to be seen from.

Thank you though.


Yes, I’m in the same spot as there are not BLFs on the WP820 that I am aware of.


I did 2 tests, unfortunately the BLF key *982100 is not needed, UCM does not make it active.
Supposing you use voice mail 2100 as a “common” box you can on all phones create the text “voice mail 2100”.
When 2100 receives a voice message the key of all phones flashes, and it is already a big step forward.
Unfortunately, however, pressing the “voice mail 2100” key is given error, as the phone dials *97 and logically goes into error.
It would be sufficient if instead of *97 the phone, by pressing the “voice mail 2100” key, dialed *98 (with the relative sequence), at that point it would be almost perfect.


Except for the fact that we are dealing with WP820s which do not have BLF keys…


we need a wall board of some form that integrates with the switchboard for vm display etc… or as i posted before… create a relay to external dc light system to signify the vm is left.


Yes, of course, but I still solved it with *98


Please explain how *98, which allow you to dial into any mailbox solves the issue of not being able to see the MWI when there is a message across so many phones. The problem being discuss is notification not access.


Are you suggesting mounting a wall board in each room a this person’s large house?


with P33=*98
what I don’t understand, how come if I’m from Zero Config (example) P33=*56, instead of sending *56 on the phone I still find myself *97. I don’t understand where this parameter comes from and how it bypasses my default model. Until yesterday it worked …
In any case, just put *98 manually on each phone and everything works smoothly.
It’s uncomfortable to have to make key "voice mail 2001+extension+pswd, but it works well, I can try to remove the pswd to make the maneuver + easy.


crazy, anything I write on P33=XXX Zero Config overwrites it with *97, I’m looking everywhere but I do not find on Zero Confg as he writes *97, this thing had never done to me, other P instead work properly.

I confirm, P33=*98 (or any other code) does not send it if sent by Zero Config Model on GXP2135, if instead P33=*98 is always set to Zero Config but on the single extension it works.

If someone wants to try it, they can try


Except that you would not know there is a message to get - NO MWI (Message Waiting Indicator).

@damiano70 if you have a solution to the problem at hand great. Otherwise you are providing a solution to something that has never been a problem.


Of course there’s a signalling.
If you believe it’s not a solution, it doesn’t matter, I try to help you, nothing more.