Acrovista Bell Commander and cloud system

[Colorado VoIP]

hello all,

we have a large charter school we just deployed setup on a cloud system. 2 sites, 2 sbcs, overhead paging, and an acrovista bell commander. everything is registered just fine and paging works, as well as the bell commander UNTIL the files played are longer than 30 seconds. we have calls terminate at 32 seconds from the bell commander, but we can have phones page for 20+ minutes when testing.

everything points to sip alg, but multiple tools indicate this is disabled on their network, the 3cx system passes all firewall checks in the cloud.

we tried to register the bell commander directly to the cloud system and it was unable to make calls at all.

note: the bell commander works with sound clips shorter than 30 seconds, no issue there at all.

has anyone tried playing clips longer than 30 seconds, and how did you get it to work longer behind a SBC? (we have a 2nd charter school using this exact setup and they play short clips for passing period bells without incident either).

Thanks,

 

[JohnS_3CX]

Calls dropping at the 32 seconds mark usually mean only one thing:

- After the call is established the ACK message is not received which causes the call to drop after 32 seconds

-You will need to run a packet capture on a device and the PBX and see capture a call. Then check the captures and look for ACK messages

- You should see one side sending 200 OK messages for 32 seconds without getting a reply and then dropping the call.

If that is the issue then you need to see which side is not sending the ACK message and pick it up from there

 

[Colorado VoIP]

this is what the bell commander has in its log. I stripped out the public IP and phone number we were testing with for security reasons.

[2020-07-16 12:43:11.933] Message: SIP: 8601 : Received SIP/2.0 200 OK
Via: SIP/2.0/UDP 10.20.26.12:6101;branch=z9hG4bK-D180C03B
Record-Route: <sip:[email protected]:5060;user=proxy;tnlid=sbc.80567a89>
Contact: <sip:[email protected]:5060>
To: <sip:[email protected]:5060>;tag=23388816
From: "XDrLCJrG3h"<sip:[email protected]:5060>;tag=C70D6461
Call-ID: 1243585
CSeq: 4 INVITE
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE, UPDATE
Content-Type: application/sdp
Supported: replaces, timer
User-Agent: 3CXPhoneSystem 16.0.5.619 (619)
Content-Length: 254


the bell commander support says the contact shouldn't have the loopback address it, but apparently behind a SBC this is normal.

still need to run a packet capture on the phone system with a call in place to see what happens.

 

[JohnS_3CX]

The existence of Record-Route takes precedence in this case, so it becomes the contact so to speak, and yes this is normal. We would expect the Acrovista device to honor it, but like I said previously

- see the captures first
- isolate the issue
- and then investigate the cause