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

[Juergen K. Zick]

Well, I have no idea how DSL lines are connected in the US but what happens 
to a normal Internet connection when the phone is being picked up ?
Test scenario could be that your Dad is listening to an Internet radio 
station or other audio stream and then being called....
BTW, how are the "real" phones and the answering machine being connected ? 
Is the HT in front of them in the POTS line ?

--Juergen



>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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