Can you recommend a free lo-fi VoIP service?

Question

Sometimes I need to talk to someone (using PCs on both sides, no landlines) having a very low bandwidth (56K and less). Can you recommend a VoIP service which could provide a connection stable enough for a comfortable talk? No matter how would our voices sound, they must be just understandable and stable.

Don't recommend Skype, it doesn't work at all, can't even sign-in after I go over my traffic limit. I suspect it is explicitly blocked by my ISP (as otherwise it'd work for text messaging at least), so I'd like to have some not-so-popular alternative which my ISP won't bother to block.

I'd strongly prefer a service which can be used natively on Linux, I'd use a Windows-only service only if it is absolutely unique and otherwise great.

Answer 1

I've used teamspeak and ventrillo over dial-up with acceptable results, especially if you are not running the server on dialup. I have also heard good things about mumble and its open source too. In all cases there are options for using low bandwidth codecs.

Answer 2

Ivan, you will need to fid a VOIP service that supports the G.721 Codec. This codec gets your voice trimmed down to as low as 24 kbps, each way. For more information calculating the specific bandwidth needs of various codecs, try visiting http://www.bandcalc.com/

Answer 3

The problem with running VoIP on anything lower than DSL, is that a typical connection uses about 100kbps up and down, a 56kbps modem obviously is not capable of handling that. I don't think you're going to find what you are looking for. Even for a 128/128 DSL line, VoIP is pushing it.