[Asterisk-Users] PSTN Incoming call on real line disrupts VoIP call over DSL circuit

[Hadar Pedhazur]

Jerry Jones wrote:
> I would guess either the DSL itself is bad or perhaps the dsl Modem. 
> perhaps calling Bellsouth would be helpful? Does other Internet traffic 
> get interrupted also?

The rest of the Internet traffic is _not_ interrupted, and his voice 
continues to be heard, so even that part of the connection continues 
uninterrupted.

I'm not sure how to diagnose whether the modem is bad or not, given that 
other traffic (and half of this traffic) continues to flow over it. I 
can only imagine calling Bellsouth and being told "we don't support VoIP 
unless you buy our VoIP service...".

Thanks Jerry!

> On May 8, 2006, at 1:42 PM, Hadar Pedhazur wrote:
> 
>> I haven't seen anything this strange, and it's 100% reproducible. I'm 
>> hoping that there are some clever ideas out there for what to look 
>> for, since I can test to my heart's desire on this one...
>>
>> My Dad lives in Florida, and has a Bellsouth DSL line. Of course, he 
>> has a regular POTS line connected on the same line. He has the 
>> appropriate filters on every jack that has a phone connected to it, 
>> and he even replaced one or two of them (when I thought that was the 
>> problem).
>>
>> I sent him a HandyTone GS-486 (HT), configured to connect back to my 
>> Asterisk server. He only has a single computer in his apartment, so 
>> it's connected into the HT, and the HT is connected into the DSL modem.
>>
>> He can make and receive calls on the HT, and the quality is excellent. 
>> If he's speaking via the HT (meaning a VoIP-only call) and the "real" 
>> phone rings, everything continues fine (temporarily). If the real 
>> phone is answered, either by a person, or by the answering machine 
>> (which is in another room, connected to a filter on another jack), 
>> then the audio on the Asterisk conversation becomes _one way_. My 
>> father can be heard _perfectly_ by the remote side of the 
>> conversation, but he can hear nothing. When the POTS line is hung up, 
>> then both sides of the VoIP call go dead (audio-wise). Of course, he 
>> can now redial a VoIP call, and both sides work perfectly...
>>
>> At first, I couldn't imagine that it was anything other than a bad 
>> filter, but other than replacing the filter (which didn't help), 
>> nothing else stops working. He can continue to use the Internet 
>> connection on his PC just fine, and I can continue to hear him speak 
>> over the VoIP connection with no problems either, so the Internet 
>> connection has not been lost.
>>
>> I have to admit to being completely clueless as to what to even look 
>> for, so _any_ advice as to things to test for would be appreciated. As 
>> I said at the top, I can reproduce this 100% of the time, so I can 
>> easily setup any debugging environment in advance, and trigger the 
>> problem at will, etc.
>>
>> Thanks in advance!
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