[TriLUG] VoIP SIP MODEM?

[Jon Carnes]

On Thu, 2004-06-24 at 10:08, sholton at mindspring.com wrote:
> Perhaps someone on the list can assist.
> 
> In a VoIP discussion recently, a question came up: 
> If I'm using pure VoIP (from IP phones on a LAN, and/or VoIP
> software on a PC) but need to connect to a modem, such as on 
> a BBS system, but don't want to use a kludge like 
>   PC -> modem -> SIP box -> Internet -> PSTN gateway -> modem -> BBS
> what kind of software device would I need for the client end?
> 
> I'd google on this, but I don't know what it would be called.
> 
> I'm thinking it would be some sort of software driver which
> looks like a modem to the kernel and apps but produces 
> and consumes SIP packets from the ethernet interface which 
> contain the CODEC-encapsulated analog squalking of a modem.
> 
> Is there a name for a beast like this?
>  

What you are talking about is simply a codec. It would take your UDP
packets (not SIP - SIP is only used for control and setup, data/voice
uses RTP which is a udp based protocol), and convert the UDP packets
into signaling that could understood by a modem.

I don't know of any VoIP codecs that do this. It would be great to have
one for faxing. Right now we have to loop the faxing signal thorough a
Fax card/modem to let the hardware inside it decode/encode the fax
signaling.

Most times we can live without faxing in a VoIP world. After all, we're
pushing around data, so we can just send the document directly - or scan
in the document and send it as a nicer picture than you would get with a
Fax.

Good luck - Jon Carnes