I havent got my tech to log what he has done so far. Lines will connect to and from remote fax machines, no handshake apparently, no talky over the devices. I will be more descriptive shortly. Sucks that he is four hours away and a rookie compared to me with telephony, not that I am much better haha
-----Original Message----- From: Fred Goldstein Sent: Wednesday, April 02, 2014 5:08 PM To: wireless@wispa.org Subject: Re: [WISPA] OT Fax over Voip On 4/2/2014 5:24 PM, Nathan Anderson wrote: > On Wednesday, April 02, 2014 6:55 AM, Fred Goldstein <> wrote: > >> But in addition to that, I STRONGLY recommend a separate VLAN for the >> voice-grade channels. With priority, or reserved bandwidth. TCP/IP in >> normal operation manages its flow rate by having packets thrown away; >> that's why the 1G LAN port on your PC doesn't blast a whole file at 1G >> into a 2M link. It uses packet loss as a signal. TCP applications >> retransmit and actual human voice is intelligible with some gaps, but >> modems, including fax, are very unhappy. > Do note that RTP is implemented over UDP, not TCP, so in VoIP, a dropped > audio packet is a lost audio packet, not a delayed or even out-of-order > audio packet (although those other two things can happen...they just > aren't a result of retransmits, or at least not a retransmit initiated by > Layer 4). > I guess my grammar was a bit rough there! So you're of course right. TCP applications retransmit. (period) Actual human voice (which doesn't retransmit, as it can't wait) is intelligible some gaps. Modes, however, including fax, are very unhappy with gaps. And stressing Nathan's previous note ("*what* doesn't work?"), this may be one of those *rare* occasions when a video (YouTube anyone?) might actually help. Although the audio alone is more important. If we could (see and) hear the call being dialed by the originating fax, hear what the ring sequence sounded like, and heard the response, with the speaker belching the CNG tone all along, it might help identify the problem. But really, fax and VoIP don't get along very well unless you really tune the VoIP network up to support it. And I know how some faxes are picky. My office fax line sat here virtually unused for years, but my wife needs to receive faxes regularly. Her fax is on a Comcast PacketCable (they call it VoIP but it's really managed VuIP) line that is shared with her office phone and answering machine. My fax (both are Brothers) can send hers a fax. The answering machine gives its spiel, starts to listen, then the fax hears CNG and cuts off the answering machine and sends modem tones. Just like it's supposed to work. But the fancy new fax server system at the courthouse just won't send to it. (Nor will some sizeable fraction of other machines.) It will send to mine, which isn't shared with an answering machine, but not one that is. Picky picky. Fax is like that. -- Fred R. Goldstein k1io fred "at" interisle.net Interisle Consulting Group +1 617 795 2701 _______________________________________________ Wireless mailing list Wireless@wispa.org http://lists.wispa.org/mailman/listinfo/wireless _______________________________________________ Wireless mailing list Wireless@wispa.org http://lists.wispa.org/mailman/listinfo/wireless