On Wed, 9 Aug 2006, Jason McBrien wrote:
So, has anyone tried using a modem over VoIP? We just
signed up through our
cable company, and have unlimited long distance dialing, so I could
theoretically dial up anywhere in the CONUS for free. I'm concerned that the
VoIP box uses some sort of adaptive noise-sensing compression what would
kill a modem connection. Has anyone given it a try?
Modems and faxes can be pretty spotty over VoIP - it depends largely on
the carrier you are using and the CODEC involved. Not to mention how the
'net is behaving on that day.
VoIP introduces delay into the line (regardless of whether a human ear
notices it), which really plays hell with cheaper faxes. I've not tried a
modem, but I imagine it doesn't help. Naturally the crappier your
connection, or should Level3 be blowing goats that day (Like it was
yesterday, grumble), the delay introduced can get up to a 1/4 second.
The big one is lossy compression CODECs which can alter the tone of the
blurbles being spat down the line. And since you don't really have any
control over what CODEC Vonage, or other VoIP providers, are using between
them and their PSTN gateways... you never really know what's going on.
Thankfully echo isn't something you're likely to come across, since that
is generated most often by handsets - and then made noticeable by the
delay inherant to VoIP... but I suppose if your modem sucks...?
Fax is not usually considered a "supported" medium over VoIP - T38 is a
digital fax protocol and is what you're 'supposed' to use when doing this
sort of thing. Smarter people than I came up with this one.
Anyways. Junk to think about. I guess it should make you all that more
amazed if it actually works semi-reliably.
JP