Create backdoor to extension on live answer system


Hello, I am a complete novice to VoIP/PBX systems but was forced into the fire when the 3 different “contractors” our hardware vendor sent to us turned out to have no idea how to set-up Grandstream’s products.

I’ve managed to get the system to a satisfactory level of set up. The voicemail set-up could use some tweaking; the group voicemail is very cumbersome the way we use it where each extension has to delete the same message, I’ve read the alternate ways and think I’ll pursue them when I have more time.

But for now my current question:

We are a small dental practice. I have a ring group set up to ring our 3 front desk people who handle all incoming calls. We are live answer.

Is there any way at all to create a back door so that one of the Dr’s wives can direct dial the extension on his desk? That phone is not part of the ring group.

We have 2 phone lines. I mention this because I think utilizing one line as a pseudo-back door might be the only possible way, however, if it requires something like any calls to that line ring his phone first and then get transferred to the group after a time out- that probably won’t work.

Thanks in advance,



Is it as simple as creating a 2nd inbound call route?

Currently the only Rule is _. being directed to the ring group.

Could I create a rule for the # of the wife’s cell and home # and direct that to his extension?

If so, since that # also would fall into the primary rule, would it also ring the ring group? That wouldn’t be terrible since this is only so she can reach him after hours. It does however look like I could use the CallerID pattern to narrow which extensions each rule apply to, if I’m reading the manual correctly…


I think you’re on the right track but just to make sure I haven’t misunderstood, I’ll try to say it back with some additional details.

Setup a second inbound rule that you keep first in the list of rules (move it to top after you create it). In the right hand box, enter the wife’s cell on one line, home phone on the next.

Direct it where you want it. Dr’s extension I’m assuming.

If it doesn’t work, double check the CDR for the two numbers and make sure you match exactly.


Inbound do not have option to move, most detailed will always be used first (if you add required number it will be most detailed anyway).
rest is as @costwisewpg write.


Unfortunately it doesn’t seem to be working.

Currently testing with my cell calling in and trying to direct it to an extension not part of the ring group.

It rings the ring group and not the extension the inbound route is supposed to direct it to.

@costwisepg my understanding is that the box on the right is to identify extensions within our PBX that the rule applies to and the box on the left is where I should be entering the # of the incoming caller?

I have tried creating the rule both with the directed extension in the box on the right and without and no joy.

Have verified that my cell # I entered into the rule _xxxxxxxxxx (where x’s are my actual #) is the same as it appears on the CID.


The box on the left is used to identify the inbound number (using SIP) that was dialed to reach you (DID). The box on the left is used to identify who called and is the callerID (CID) matches to then direct to the destination you stated below.

So, assume your phone number is 999-555-1111. In the left box, you would enter in this number (you can input +19995551111, 1999555111 and 9995551111 where each number is on a different line). Not knowing how your provider is sending the number is why I have suggested the combination as the arrangement will fit most formats for the US.

In the right hand box, enter in the callerID info. So assume, one of the doctor’s wives calls. You would enter in her number (the number she would be calling from) into this box and in this case assume it to be 9994442222 and again you may need to have them call and then look in the CDR to see how her number is formatted. Once determined, then enter it into the right hand box as seen in the CDR.

At the bottom, select the doctor’s extensions to where his wife’s call should be directed. If the doctor has other numbers that should be sent his way directly, you can also enter these into the same right hand box.

The re-create the same rule as above but:

  1. Leave the right hand box empty
  2. Direct the call to the desired destination/ring group.

The rules are processed in order, so the one with the CID info needs to be first/topmost as otherwise the wife’s call will come in and will go to the ring group. The rules are structured such that the first match to a rule will apply and by not inputting the wife’s CID info, we told the system to not look or care about CID.


Thank you for the detailed write up; it however did not work for me. I might, when it gets quiet at lunch time, drop all the rules and only have one set up for the specific number inbound rule to the extension and see what happens then.

Perhaps I did not give enough background detail- and perhaps this is not even possible with our system.

We have 2 analog lines that run into this PBX system, it is not actually a VoIP service provider.

Could that be the issue?

I have been setting these rules up under the Trunk titled “SIP Trunk - Spectrum”

There are also 2 analog trunks in the drop down, one for each line.

I can add rules to those trunks, but the left box is locked to “s” on each.


If analog, same principle if your provider is sending CID info and the UCM is set to pass same.

With analog, your number is tied to the physical line so there is no need or way to add a DID (left box) as when your number is called, unlike SIP, the provider sends a ring voltage down your line to signal the UCM about the call. As you have two lines, each has its own number and presumably when one is busy, the provider will send a 2nd call to the other line, if available and ring it instead. If both are busy, then the caller should get a busy as the UCM does not support call waiting.

You need to create the same kind of inbound rules as described for SIP, but using the pull down to select the analog trunks instead of Spectrum. As you cannot nor need to do anything about a DID you merely need to enter the CID info, but as you won’t know on which trunk the call may come, you need to duplicate the rule for both trunks with the CID info and destination.


Thank you, I will add the rules to the analog trunks and see how it goes.



I did have to add " _. " to the callerID (Right side) box on the analog trunk however (for the 2nd, general/all other callers rule). Leaving it blank, like it was originally, after adding the specific rule 1st, resulted in an incoming call getting a “number unreachable” message. Not sure why but populating that box fixed it.


It should be the CID number, not just ._


The 1st rule is the CID # of the wife directing to Dr extension

The 2nd rule is the general rule for all other incoming calls, directed to the reception ring group.

The CID box on this rule was previously blank (when it was the only rule), however when left blank after adding the 1st rule, other callers were unable to dial-in. Adding the _. specification allowed all other callers to be routed correctly to the ring group. _xxxxxxxxxx probably would have worked as well, it just seemed to need further direction since a primary rule was added.

Sorry for creating confusion, this stuff is still very new to me and getting my point across without knowing the vernacular is difficult.

I do appreciate all the time and helped me get this up and running.


Ahh, got it, Great.