VOIP Question

Archived from groups: comp.dcom.voice-over-ip (More info?)

Joe wrote:
> I'm not quite understanding what the deal is with the charging for a
> SoftPhone by these various companies. The network traffic sent out by
> your hardware VOIP router has to conform to TCP/IP standards, right?
> I'm not sure I am understanding how these providers can detect the
> traffic is being generated by the hardware device or a software device?
> Techincally, isn't it possible to sniff the outbound traffic from one
> of these hardware devices and pull out the necessary information from
> the packets, plug those settings into a SoftPhone and then disconnect
> the hardware device and utilize the SoftPhone?

That's not that easy, because the password is not sent in clear.
Usually the authentication is based on a challenge-response mechanism
where the server sends a random string (nonce) and the client sends
back a cryptographically secure hash of the nonce with the password. As
reversing a secure hash is computationally hard, recovering the
password is not trivial.

Still, providers which charge on metered basis for anything different
from calls to or from the PSTN (regardless of the device used to place
them) are just asking to be dumped... In fact, thanks to open standards
like SIP or IAX, users can follow a DIY approach by buying their own
equipment (or using softphones) and then choosing separate providers
for PSTN termination, DiD numbers where to receive incoming PSTN calls,
and registrar function for (free) Internet-to-Internet calls (e.g.,
FreeWorldDialup). Bundles may sometimes offer some savings, but in that
case I'd recommend to choose providers offering flexibility and no
restriction on number of simultaneous calls. One I can personally
recommend (although I can't comment on DiD numbers because I'm not
using them) is www.teliax.com .

Enzo