Everyone wants to cut costs these days. We had a tall order from a customer to move a bunch of POTS lines to a PRI and then bring them from their PRI to the fax machines. In order to do this reliably on the LAN we used a protocol called "t.38", which is how faxes can reliably transmit over a data network. It's not an easy thing to do unless you have the correct equipment. This means the internal office fax machines have to connect to voip FXS adapters (or gateways) which support t.38. The customer PRI gateway also has to support it. In our case we planned properly and all the hardware was already capable.
We're taking this a step further and get faxes directly to our pbx (sipxecs via t.38), because then my faxes get emailed to me and I manage that all from my phone system. While I understand and respect why someone would want to use a PRI, there is no way to do DID faxing on analog lines, since only one line equals one number. So aside from a PRI, the only other way to do this is with a BRI gateway, which costs astronomically, assuming your local telco can provision DID numbers to it. Most of them can but have noone left that knows how to do it, which is "old timer alchemy". The other way to do this is with sip trunks.
With sip trunks, you need to ensure the ITSP does support t.38 on incoming calls and can guarantee a 100% t.38 inbound route. This means the ITSP must receive the call, probably on a PRI, and transcode it to t.38 and send it to you. The ITSP t.38 format must also be syntactically correct. The upside is, your faxes come in from the Internet like a regular SIP voice call, are captured in your CDR records, managed by your phone system, and email to your user with no modems, physical phone cords or fax machines. The downside, finding one that works like advertised and doesn't cost an arm and a leg too.
Why we are doing this instead of using an online service? Easy -- those online hosting firms charge a monthly fee and a per page premium over your basic "number of pages" for receiving faxes. Since customers are looking to cut costs right now, we'll try to provide ways to do that. The current tests have the following costs associated with them:
Setup fee per number -- $8.00 Monthly Fee per number - $2.00 Per minute cost (not page) - .0191 cents
So at 2 cents per minute, with an average page taking a little over 30 seconds, that's 1 penny per page and in our testing with a heavily marked up page it's about 1.25 cents per page. It's pay as you go, and for a 1 penny per minute premium (or pay 3 cents per minute and use a toll free number). When you compare that with the large online fax companies, the minimum is 10.00 per month (per number) with 200 pages included, and each additional page is "10" cents each. If you received 500 pages per month, the hosted firms charges you 40.00, whereas your internally hosted t.38 service would cost around 10.00.
We've already tested with a couple of providers and the configuration we chose to use above is what we are writing about!
Why is this an Internet fax? Because the call comes into your phone system from the carrier and receives it like a fax machine does, then emails it out to you, only the phone system is getting the call over the Internet directly and not from a phone line.
-- Stay tuned for Part 2, how we send t.38 from our old fax machine out through the same connection/account, and make it a seamless dialing plan in having our gateway choose the provider knowing it is sending a fax, so no funky access codes to dial either!