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brett111
Beginner

Phantom calls every 4 minutes on a pair of analogue phones

My setup is as follows:

Analogue phone > ISR 4321 > Simulated WAN Router > ISR 4321 > Analogue phone

The ISR 4321s are using NIM-2FXSP modules to connect to the analogue phones.

 

I have the routers configured to automatically ring the other phone when the phone is picked up/ off hook. This works correctly.

My issue is that every 4 minutes phone A will ring phone B, and 2 minutes later phone B will ring phone A while the phones are physically on-hook. I have attached the running config of one of the routers. The voice-ports are configured (by default) as loopStart. The phone numbers that are automatically called when the phones are off hook are 10801 and 10901.

 

I have found out that when phone B rings, phone A will show as off hook and when phone A rings, it is shown as receiving a call.

Normal (no ringing)

--------

b-rtr-01#show voice port summary

IN OUT

PORT CH SIG-TYPE ADMIN OPER STATUS STATUS EC

=============== == ============ ===== ==== ======== ======== ==

0/1/0 -- fxs-ls up dorm on-hook idle y

 

 

Phantom Ringing on B Phone

------------------------------------

b-rtr-01#show voice port summary

IN OUT

PORT CH SIG-TYPE ADMIN OPER STATUS STATUS EC

=============== == ============ ===== ==== ======== ======== ==

0/1/0 -- fxs-ls up up on-hook ringing y

 

 

Phantom Ringing on A Phone

---------------------------------------

b-rtr-01#show voice port summary

IN OUT

PORT CH SIG-TYPE ADMIN OPER STATUS STATUS EC

=============== == ============ ===== ==== ======== ======== ==

0/1/0 -- fxs-ls up up off-hook idle y

 

Im wondering if there is some form of keepalive or repetitive signal coming from the FXS port or from the phone itself.

Has anyone got any ideas?

1 ACCEPTED SOLUTION

Accepted Solutions
Adam Pawlowski
VIP Advocate

It depends what your analog phone is in this case. Some devices try and sense the line by taking it off hook momentarily, which could trigger this.

View solution in original post

4 REPLIES 4
Nithin Eluvathingal
VIP Advisor

I can see plar configured on the port. If you lift the handset, it dials the number mentioned in the plar. 

 

 

 

 

 



Response Signature


That's correct, the issue is that the phantom calls happen when the handset is physically on-hook/ in its resting position. Calls do work correctly when I lift the handset off the phone.

Adam Pawlowski
VIP Advocate

It depends what your analog phone is in this case. Some devices try and sense the line by taking it off hook momentarily, which could trigger this.

View solution in original post

I purchased a pair of dedicated analogue hotline phones (INTERQUARTZ 9826N SLIMLINE HOTLINE TELEPHONE IN RED 9826NK) to replace the phones that were phantom ringing. I can confirm that the hotline phones work correctly and do not cause any phantom ringing.

 

During my testing, i found out that if i used a one hotline phone and one standard analogue phone, after two minutes the hotline phone would phantom ring once then not phantom ring afterwards so i think for some reason when phone B rings phone A, it must set off some form of countdown for it to try sensing the line.

 

Thank you for the help.

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