J Poz wrote:
Using an analog line is not an option for my service. My application runs on a ROOT SERVER of an ASP. So I can do anything I want to the server but I can't connect to or get external analog lines. So my options are doing faxing via the Internet (VOIP/SIP) or use a faxing service. But my experience with faxing services has not been too good as I've mentioned.
Traditional faxing (not T.38) pretty much requires a lossless audio channel. Normally the best way to get this is with PSTN channels/lines through a Zap device. That said, VoIP channels can be configured such that they are also lossless. IAXmodem, for example, functions on the premise that an IAX2 channel passing over the loopback device will be lossless. I have also seen lossless SIP and IAX channels running over a WAN, but they were very specificially configured, and I wouldn't expect most connections with traditional VoIP providers to be anything near the kind of losslessness that is required for this to work well.
For the most part, I suspect that those VoIP providers that promise fax support (over VoIP G.711) are doing so on a type of gamble... that ECM support of most fax machines will compensate, that they can control enough of the communication to mitigate the problem substantially, and that the remaining (say, 10%) error rate will not cause significant enough complaints from the users to cause it to be unprofitable.
So, be forewarned that faxing over VoIP channels is usually not going to work extremely well for you... not unless you can mitigate the problem by creating near-lossless connections between you and the endpoint with the PSTN connection.
Lee. _______________________________________________ --Bandwidth and Colocation provided by Easynews.com -- Asterisk-Users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
