[asterisk-users] Got event 17 (Polarity Reversal)...

[Gordon Henderson]

On Mon, 13 Oct 2008, Jorge Mendoza wrote:

> Gordon Henderson wrote:
>> On Sat, 11 Oct 2008, Jorge Mendoza wrote:
>>
>>> I founded this behaviour in the past. When the CO provides reversal
>>> polarity and the FXO port is configured to ignore polarity events, then
>>> a reversal polarity could be detected as ringing if the
>>> hardware/software is not well designed or configured.
>>> So, if the CO provides polarity reversal, why not set answer and release
>>> supervision to yes?
>>
>> We need the flexability to answer either way...
>>
>> Here in the UK the (BT) exchange will do a polarity reversal to signal
>> incoming CLI - it then send the CLI, *then* sends the ring signals, so
>> answering on polarity reversal would be wrong.
>>
> Answer supervision on reversal polarity applies only to outgoing calls,
> not incoming ones.
>> They also do a random polarity reversal most nights too - some sort of
>> automated line testing. Eg. from my home box:
>>
>> Oct  7 01:40:28 NOTICE[15581] chan_zap.c: Got event 17 (Polarity Reversal)...
>> Oct  9 03:53:06 NOTICE[19904] chan_zap.c: Got event 17 (Polarity Reversal)...
>>
>> Note the times...
>>
> Are they just warning alarms or they starts phantom calls?

As far as I know, it's BT testing the line - what they actually do, I've 
no idea. Fortuantely asterisk doesn't think it's an incoming call and ring 
all the phones..

Gordon