Q: Intermittent call drops at 15min (exactly)

[fortech]

Hi, I'm curious if this sounds vaguely familar. I've got a 3cx setup I'm managing for a client. Setup and issues:

- 3cx deployed via 'pbx exporess' running on an OVH Public Cloud/Openstack VM in Montreal
- SIP trunk to VoipMS / supported template built into 3cx for this sip provider.
- SBC gateway in office in Nova Scotia and some physical supported grandstream handset voip phones.
- additionally staff use 3cx soft phone app on iphone/android smartphones. So it is a mix of users on 3cx SmartPhoneApp plus Grandstream physical phones behind an SBC.

It appears that some inbound calls are dropping intermittently at 15minutes. Not all calls. But some. Not any specific client device -it might be a grandstream one time, it might be a 3cx softphone app the next. Not for any specific user - any user on the system.

To try to debug things we added a different SIP Trunk with different carrier for all outbound calls. (Another supported voip carrier with a template in 3cx). These outbound calls via other carrier appear immune to call drops at 15min. So it is only for "Some, not all" Inbound calls of >15min duration which appear to be randomly selected for the 'drop,bye" lottery.

I'm curious if this sounds familiar to anyone / if there are things I can look at to debug. I was under impression the SBC and 3cx app config meant we are more or less not doing vanilla UDP SIP from client devices over public internet to the 3cx server / and that those connections are all pretty 'controlled' and in theory 'reliable'.
(ie, immune to foibles of a client site firewall for example)

I did peek at some other threads. Reviewed our settings for our VoipMS SIP Trunk. "options" we do NOT have "Supports Re-invites" Ticked/enabled. Which I gather is likely the desired config.

I am not sure if I can hope to get more meaningful info if we carefully record when the drops happen and dig into logs on 3cx
or if this is some weird issue from VoipMS and 3cx not playing nice some of the time

but any comments or pointers are greatly appreciated.

Thanks,

Tim

 

[ChrisC_3CX]

The fact that this only happens with one particular SIP Trunk does indeed suggest that the issue may be related to the provider or specific SIP Trunk. Just to clarify, you said you added an additional SIP Trunk with a different carrier for outbound calls. Is that to say that you have not tested Inbound calls with this carrier, or have you and the issue still occurs here as well? Also, what exact version of 3CX are you running?

What I would recommend first in regards to troubleshooting, is to first determine who is ending the call to hopefully narrow down where the issue might reside. You could do this by first enabling Verbose Logging mode in Dashboard >> Activity Log >> Settings and then check the Activity Log for of an affected call in Dashboard >> Activity log to hopefully figure out if it is the 3CX PBX ending the call or the SIP Provider.

Note: You can use the "Filter" option on top to filter the displayed calls.

 

[StefanW]

first, guess - Session Timer messages fail to be answered and the call is therefore declared "unmanaged".
The result is that the call will be dropped...

 

[mixig]

first, guess - Session Timer messages fail to be answered and the call is therefore declared "unmanaged".
The result is that the call will be dropped..

Second guess, enable support re-invite on that trunk and see is there any changes

 

[ChrisC_3CX]

@fortech
I'd recommend not deviating from the SIP Provider's default template at least until you have identified the issue. Using the default template configuration should ensure normal functionality with the SIP Provider in question since the default settings set for each provider have been determined through extensive testing by 3CX in cooperation with the SIP Provider.

 

[StefanW]

Second guess, enable support re-invite on that trunk and see is there any changes

nononono that is a bad move and you will break a lot, first of music on hold and that's not the worst which will happen 100%

 

[mixig]

nononono that is a bad move and you will break a lot, first of music on hold and that's not the worst which will happen 100%

I know that, but what if provider request re-invite support and with that MOH is not working after that? I have same situation, provider is not supported with 3cx and they blame 3cx for that, with both option enable/disable I have problems, call droping after 15 min or no MOH...

 

[ChrisC_3CX]

I know that, but what if provider request re-invite support and with that MOH is not working after that? I have same situation, provider is not supported with 3cx and they blame 3cx for that, with both option enable/disable I have problems, call droping after 15 min or no MOH...

I can't recommend any specific SIP Trunk configuration for unsupported SIP Providers since they have not been tested with 3CX, but when talking about 3CX supported providers, the settings defined by the default template are the ones that must be used for guaranteed smooth operations. In the event where issues surface despite having all default settings, we must first identify the cause and then act accordingly. Whether or not the current default configuration for a SIP Provider will be re-evaluated will depend on the situation.

 

[AndreasP_3CX]

@fortech. Check the session timers first as per StefanW's advise. The 15 minute timeframe is a hint that that is where the problem most likely is.