Solved Obi110 as FXO port in 3CX v16

[marche]

I have setup Obi110 as a Gateway (FXO) port in 3cx according to this forum: https://www.3cx.com/community/threads/solution-to-using-obi110-with-3cx-phone-system-v10.21295/

I get successful registration and I am able to send calls from my softphone through 3cx to the Obi110 and to the LINE port of the Obi successfully. However, I am only able to send one call. After that, I get this:

04/07/2020 1:11:22 PM - Call to T:Line:10000>>106@[Dev:sip:[email protected]:5060] from L:23.1[Extn:100] failed, cause: Cause: 503 Service Unavailable/INVITE from 192.168.1.250:5060

where 192.168.1.250 is the Obi

The only way for me to call again through the LINE port, is to reset the Obi.

I have checked, the Obi returns to the On-Hook state when the first call has ended, so its not keeping the line engaged. When I change the X_InboundCallRoute in the Obi to ph, I don't get the 503 service unavailable, and I am able to place multiple calls in succession successfully.

Anybody have any idea on how to get this to work?

 

[AWS2P]

I have checked, the Obi returns to the On-Hook state when the first call has ended, so its not keeping the line engaged

is it the same on 3cx side ? do you see on dashboard 0 call too?

 

[marche]

yes, the active calls becomes 0 when I hang up on the softphone.

 

[marche]

For those also in the same issue, as well as for my own future reference, I was able to figure this out.

As it is currently connected to an extension of my Panasonic analog PBX (TA308), I tried to connect the LINE port directly to the FXS port from my PSTN Provider, and the Obi works well, making calls successfully one after the other. So it made me realize the problem was the PBX and a setting in the Obi.

Doing a syslog dump of the Obi for a call, I notice this after placing one call after reset:

<7> FXO:NewTermState:line in use
<7> RxFrom:c0a801ad:5060
INVITE sip:[email protected]:5060 SIP/2.0

and returns 503 Service unavailable after that.

I checked the manual - apparently there is a little known feature of the Obi - "line in use", that monitors the PSTN (LINE PORT) if there is a parallel'ed phone still using that same line (hence making the line unavailable for use, even if it is already On Hook for the Obi). The default setting will say "line in use" when the voltage is 25V or below.

Checking my LINE PORT, the default On Hook state is -25V (from the Panasonic PBX)


Hence, I changed the LineInUseVoltageThreshold to -30V, so when the Obi returns to On hook state, (= -25V), the Obi will NOT say "Line in use" and release the phone properly.


And now the Obi works fine and releases the LINE properly!

Hope this can be helpful to somebody in the future.

 

[leejor]

I came across the same issue about a dozen years ago using an SPA3000, connected to an extension, off my Mitel SX-20 PBX. As the PBX voltage output was 24 VDC as opposed to the standard PSTN voltage of 48VDC, the settings also had to be changed or the line would always appear engaged. The default values of almost all FXS gateways are for use with standard PSTN values.

 

[marche]

Yes, but I initially didnt suspect the Obi, as the status of the line is ON HOOK as per the status, and based on the BLF of my analog PBX, the line is also on hook. So I looked elsewhere, just to come full circle back to the Obi and its parallel line in use detection.

 

[AWS2P]

Nice to share detailled fix , thanks even i 've no OBI