Argh! Outgoing PSTN nightmare with 488
Hi all
I have a (new) Handytone 488.
I have registered with various SIP provider and can make/receive calls. I can receive PSTN calls.
I CANNOT make PSTN calls!
I cannot, however, make PSTN outgoing calls. It drops a connected call after about .5 a second.
Bizarrely, if I connect the outside line, and ring "***", I hear the Telewest "attendant" saying "The number you called" etc, perfectly fine.
If I connect outside and ring 123, and it picks up, one end drops the call.
SYSLOG from the first example (in reverse order) :
1367DAA Hangup 2
FXO killcall 0 1 33251 0
1367DAA Hangup 4
1350DAA Pickup 2
SYSLOG from the second example (in reverse order) :
1367DAA Hangup 2
(I hangup handset here)
1367DAA Hangup 2
FXO killcall 0 1 0 0
1350DAA Pickup 2
Something (killcall) kills the call, and I see a Hangup "2" rather than a "4". I also see another "2" when I actually disconnect the handset.
I suspect this is something to do with voltage and impedance.
Port FXS (the handset) has the following options :
Onhook threshold : 800ms
FXS Impedance : UK/New Zealand #2 (370 Ohm + 620 Ohm||310nF)
Onhook Voltage : 36V
Polarity Reveral : NO
Port FX0 (the line, connected to Telewest) has the following options :
PSTN AC Termination : 370 Ohm + (620 Ohm || 301nF)
Now, the Telewest FAQ says (on Network Termination Impedance) :
The impedance necessary to satisfactorily terminate the Telewest network interface at the NTP so as to prevent instability is represented by a three-element network consisting of a 620 ohm resistor in parallel with a 310 nanofarad capacitor, both in series with a 370 ohm resistor.
My FXS Impedance matches this.
My handsets are cordless DECT, but I have tried with a wired handset. No difference.
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