Phone line "resets" when dialing out with a V.90 modem

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Joined: Sun Jan 31, 2010 9:01 pm

Phone line "resets" when dialing out with a V.90 modem

Post by zqfmbg » Sun Jan 31, 2010 9:13 pm

First off, I know people say that modems aren't supported on Ooma and may not work. That's fine. However, the failure I'm running into seems to be very artificial, and probably some kind of a bug somewhere in the system (as opposed to a simple case of compression messing stuff up).

I'm curious to know if my alarm system will be able to get updates over the line. The alarm system (Brinks/Broadview) dials a number (800-495-3555) that is basically a standard V.90 modem pool. So I figure dusting off my old external Sportster 56K and plugging it in would make a good test. :)

I'm running with fax mode enabled. About 40% of the time, connections succeed (be they at full V.90, or falling back to V.34). Of the remaining 60%, a high proportion of connections fail when the Ooma connection appears to reset itself. Listening to the speaker on the external modem, I can hear the connection negotiation proceed, but at some point (the timing of which appears to be variable), I suddenly hear some part of the negotiation go away, replaced instead by the Ooma dialtone playing. If the connection succeeds, then I can stay connected apparently indefinitely.

I don't think I've had this problem with voice calls. Anyone else ever try something silly like this? If the thing connects often enough (and hey, 40% may be often enough), then I don't see any reason to bump the whole system up to Internet or GSM monitoring, especially since alarm signals themselves (which go out to a separate phone number with a separate protocol) seem to make it through all the time.

Oh, and as a point of interest: the one-way delay for voice seems to be negligible (less than 100ms), but the Sportster claims the round-trip delay is at least 450ms. And it won't complete V.32 negotiation at all. Weird. :)

Posts: 7208
Joined: Tue Jan 27, 2009 12:49 pm
Location: Pennsylvania

Re: Phone line "resets" when dialing out with a V.90 modem

Post by murphy » Mon Feb 01, 2010 4:51 am

Limit the modem to 9600 baud.
Alarm systems use very old technology and probably don't exceed 2400 baud if they even go that high.
Customer since January 2009
Telo with 2 Handsets, a Linx, and a Safety Phone
Telo2 with 2 Handsets and a Linx

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