SPA 3102 with multiple phones connected to FXS

[cavallad]

Hi, I have successfully (nearly) connected a SPA 3102 to my legacy POTS system, so that the unit bridges the phone line, with the incoming wires connected to the FXO and the FXS connected to the legacy extensions within the house. The idea is that two DECT phones should be attached to the one FXS port. Incoming calls are routed to an Asterisk system which then rings the FXS port. It works fine for outgoing calls, but there is a 10-15s delay for incoming calls to ring the legacy phones. In addition, only one of the phones rings! A similar phenomenon occurs when ringing the FXS port from another internal Asterisk extension.

PSTN ---> FXO/SPA 3102 ---> Asterisk ---> FXS/SPA 3102 ----> Phone 1, Phone 2

I have set the 'PSTN Answer Delay' to '0' seconds in the PSTN Line tab, but it occurs to me that the additional length of wire now attached to the FXS port (at least 30m) imposes an extra impedance on the FXS port. Do I need to change this, or indeed the voltage settings for the FXS port to enable both phones to ring simultaneously, and immediately? And what should the new values be?

Thanks in advance

David

[aneagle]

Ring detector on one of the phone is more sensible than on the other and it drains ring current. Most of the phone ring detectors are made for almost 100V p-p ring signal and the spa ring signal is far lower.

[cavallad]

Thanks, aneagle. I have changed the settings in the 'Regional' tab to the following, based on the fact that I am in the UK:
Waveform = Trapezoidal (previously Sinosoidal)
Voltage = 90 (previously 70)
Ring frequency = 20 (previously 25)
CWT frequency = 400@-10 (previosuly 440@-10)
This has reduced the ring delay, but I still only have one phone ringing.
I am thinking of increasing the Ring voltage still further, but do you think this is a good approach, or is there a risk of damage to the equipment?
Curiously, both phones are Panasonic DECT, but one is circa 4 years older than the other. It is the older one that is not ringing.

[aneagle]

There's no risk at 90V, these phones should have voltage surge protector. You can try to remove the new phone and see if the old one detects ring signal. If the only old one connected and can detect ring it means the new phone eats too much ring current and makes the ring voltage to drop below the detection threshold of the old phone. It would be better to have one DECT with 2 handheld units.