Phone ringing after hanging up

[AnchorIT]

I have 2 Grandstream HT802 set up at 2 different locations and my SIP trunk is flowroute. At my first location I have not experienced any trouble with the phone but at my second after someone has called in and hung up the phone will ring again several times. The caller ID will be something like 101, 2001. Of course if you answer it there is no one there. It's been happening every day. If anyone can offer a suggestion I would greatly appreciate it.

 

[complex1]

Hi,

Make sure next parameters are set to YES
- Validate Incoming SIP Message
- Check SIP User ID for incoming INVITE
- Allow Incoming SIP Messages from SIP Proxy Only

 

[AnchorIT]

Thank you for the reply.
If I go to Settings > Parameters in 3CX I do not see any of the options you listed. Am I on the wrong page?

 

[leejor]

Settings are in the phone itself.
https://help.vantact.com/index.php?...e/View/4/2/grandstream---incoming-ghost-calls

 

[cobaltit]

Well in the ATA in this case.

 

[leejor]

Yeah, sorry..."device". Don't use a lot of Grandsteams, in the back of my mind, the "HT" should have clicked that it was an ATA.

 

[AnchorIT]

Well I tried the suggestion and now calls won't go through. Even if I change the settings back the phone continues ringing and eventually the call will fail saying the number is unavailable. I've tried reuploading the configuration file and reinstalling the firmware on the Grandstream but I'm not having any luck. If those settings are set to YES then the call immediately fails.

 

[leejor]

The fact that the phones are ringing right after you hang up is odd. "Ghost calls" are more random. Did you check the 3CX Activity log to see if there is any record of the call passing through the PBX?

I have seen other, similar issues, not involving 3CX, where, the current call is not actually disconnected, as a hook flash was seen, and the "system" (ATA?) attempts to ring you back as it thinks the caller is now on hold.

In some cases (depending on settings), a voicemail left, while on the phone, will trigger a ring notification, after you hang up.

 

[AnchorIT]

I actually don't see the call going through 3CX, I've called the location several times and don't see a record of my number. If I call my first location then the call does go through. They are set up the exact same way so I'm really scratching my head here. I'll probably redo the install queues and everything else on 3cx side to start fresh and go from there

 

[AnchorIT]

I finally went to the location and found that employees had disconnected the phone, so that just wasted a lot of my time troubleshooting. While there I attempted the options you mentioned and found that the only option that still allowed calls to go through was -Validate incoming SIP message. With the other options it would tell me that the number was invalid. The Allow Incoming SIP messages from SIP Proxy Only option also blocked calls.

 

[cobaltit]

So the recommendations given were to protect against ghost calls which I'm not sure is the case. It sounds more like SIP issue where the hang-up is not getting processed so what looks like a new calls coming in as actually the same call since the far end never terminated it. Do you have the ATA setup as ATA in 3CX or as an extension? If the later is the case I'd try playing with the 'Supports Re-Invites' and 'Support Replaces header' options.

 

[eddv123]

Point to note here, Gateways and ATA's are not supported in certain configurations with remote locations only local to 3CX, in the same subnet and/or locally routed subnet (including site to site VPN) as per the guide here: https://www.3cx.com/voip-gateways/grandstream-ht-fxs/

How have you got this setup ? if using remote STUN then this would not be good for security. There is a guide on how to set this up here but I would recommend if possible using secure SIP and SRTP:
https://www.electronicfrontier.co.uk/wp-content/uploads/2018/05/Grandstream-HT701.pdf

 

[AnchorIT]

So the recommendations given were to protect against ghost calls which I'm not sure is the case. It sounds more like SIP issue where the hang-up is not getting processed so what looks like a new calls coming in as actually the same call since the far end never terminated it. Do you have the ATA setup as ATA in 3CX or as an extension? If the later is the case I'd try playing with the 'Supports Re-Invites' and 'Support Replaces header' options.

The ATA is setup under FXS/DECT and each has one extension tied to it

Point to note here, Gateways and ATA's are not supported in certain configurations with remote locations only local to 3CX, in the same subnet and/or locally routed subnet (including site to site VPN) as per the guide here: https://www.3cx.com/voip-gateways/grandstream-ht-fxs/

How have you got this setup ? if using remote STUN then this would not be good for security. There is a guide on how to set this up here but I would recommend if possible using secure SIP and SRTP:
https://www.electronicfrontier.co.uk/wp-content/uploads/2018/05/Grandstream-HT701.pdf

That first guide is the same one I used to set this up, the model for my ATA is Grandstream HT802 but everything else appears the same. The machine running 3cx is actually on google cloud platform so definitely not local. 3CX is configured to use Flowroute as the SIP trunk. I have one DID for one location and another for the second.

 

[AnchorIT]

Right now I moved everything to a different port to see if that helps and so far I havent seen it ringing randomly but I've only been observing it for about 20 minutes

 

[AnchorIT]

Right now I moved everything to a different port to see if that helps and so far I havent seen it ringing randomly but I've only been observing it for about 20 minutes

It's been several days now and I have not heard any complaints from workers regarding the phone ringing randomly without customers. It seems changing the ports worked.

 

[leejor]

Until they find the new ports...if, that was the original problem. Once a hacker has "hit" a SIP device, that IP appears to be "flagged" and later attempts are made. They will probably do a scan looking for any open ports. In the past, some users had reported changing the 3CX PBX port from 5060, to something not commonly used, will mixed results.