[TriLUG] VoIP SIP MODEM?
Aaron S. Joyner
aaron at joyner.ws
Mon Jun 28 10:25:28 EDT 2004
David Rasch wrote:
>On Mon, Jun 28, 2004 at 08:47:24AM -0400, Alan Porter <porter at trilug.org> wrote:
>>>What you are talking about is simply a codec.
>>It's funny, the cellular companies do the same thing. At least, the GSM
>>providers (Cingular, AT&T Wireless) do for "circuit switched data" calls.
>>You buy an all-digital phone, and you hook it to your PC to surf the net.
>>You would think that you've got an end-to-end digital connection.
>>However, your ISP doesn't know anything about cell phones... they are
>>expecting you to dial up using an analog modem. So the cellular company
>>routes data calls through a bank of out-dial modems!
>>cell phone --- tower --- switch --- modem pool ~~~ ISP modem --- internet
>>In Europe, the GSM providers offer a chioce between analog modems or
>>ISDN, so it's possible to go all-digital. Here in the US, many carriers
>>(Sprint, Verizon, Alltell) are using the CDMA standard. Rather than allowing
>>you to call an existing ISP's modem, they simply act as the internet service
>>provider themselves. You get the all-digital connection, but then you're
>>forced to use the carrier's internet service.
>You can always dial up to ISDN using your cell phone, this makes it an
Only if your provider allows you to dial-out ISDN. Ironically, my phone
supports it as a setting, yet when ever I try to set it and dial our
ISDN numbers here at Intrex, it bombs. The only explanation I can offer
being that Cingular routes all calls out as analog calls, regardless of
what the phone requests.
Aaron S. Joyner
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