Unanswerable Calls UCM6301

Grandstream VoIP
1

All,

I’ve got a problem with random inbound calls that are unanswerable. They come in through a IVR with a selection of 3 hunt groups. Option 1,2 and 3.

The calls ring through the first group of customer service, and then into the second level hunt group that rings more phones. The call shows a known customers caller ID, but no matter what we do, we cannot pick up these calls. It just keeps ringing.

Any suggestions?

Here’s my extension where I tried to answer it from the log. I’m ext. 2203.
image

My vendor opened a support ticket, and they suggested a change on the phone handset config. I feel like it should be a system issue and not a handset config, but I’m new to this. Here’s support’s suggestion:

Just to double-check, does this issue happen to the UCM or the phones? If just the phones, it could be possible that they are getting ghosting calls from a breach going to the SIP port of the phones reachable from the public network.

You can resolve this issue by logging into the phone Web interface → Account → Advanced Settings:

+ Accept Incoming SIP from Proxy Only: checked.

  • Check SIP User ID for Incoming INVITE: checked.

And, under Phone Settings → General Settings → Use Random Port: checked.

2

Can the calls be answered during the first ring/hunt group before it goes to the next one?

3

I don’t know. It’s only happening once every few days, but becoming more frequent. I’m on the second level, so I don’t know if my customer service folks are busy, or if the call can’t be answered at the first level either. I’ll try to figure that out. Everyone on the first level is also on the second level hunt group, so that makes it tough to determine.

4

Edit the groups and make sure “skip busy agent” is not checked.

5

Ok, that was enabled on level 1 of that string. I’ve gone through and unchecked it for those groups.

Thanks.

6

Ok, next batch of calls after I made that change, and we couldn’t pick them up. I changed it back for now.

7

That is usually what I have found to be enabled that would prevent another person from taking the call. When you made the change no one could answer on the first ring group? How long did you wait? On the extension settings themselves, under features make sure Call Waiting is checked.

8

I haven’t had much time to evaluate that change yet. I saw some specific uses of that setting, so I want to run it by my install vendor to see if he had a reason for using that setting in some places, but not others.

9

I have lots of small installs with all the phones ringing when a call comes in. Small ring group. If that option is checked, whoever is already on a call won’t be able to answer the next incoming call. I’ve seen this mess up calls even if your extension is ringing.

10

Wait – is your UCM exposed directly to the public Internet?

11

Number of call/line keys?

12

I give most user 2 or 3 line keys. But that’s a good thought, if not programmed right it could prevent answering.

13

Got it NAT’ed through Edgerouter 12 and only opened required ports.

14

I have 2 call lines per extension.

15

We strongly suggest not opening the SIP ports 5060/5061 nor 8089 to the public internet. You are only asking for issues with hacking attempts and extra traffic hitting your PBX and using resources.

If you must open ports I would suggest using an ACL to only allow traffic from your VoIP provider through to the PBX.

If you have remote users we recommend using Remote Connect or a VPN.

16

Thanks for all the suggestions guys. I’ve identified a few things we’ll need to do on our side. I’m going to try and get rid of those open ports. I’ve seen hacks hit my remote phones, so I suspect that could be part of our issue. We’ll make those changes, upgrade the firmware on our router, and see where that gets us.

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