Originally posted by JWRacedog:
...However, particular modems are a problem. I get much better results from an external modem. The internal ones work fine sometimes and don't work at all other times. I have no idea why they are like that.
Most of our phone systems have internal manufacturer-provided modems---so they are all the same...
One reason for this is probably because many external modems include a coomunications controller. Most internal modems hand off comm functions to the main processor or the onboard input/output chipset which is doing many other things as well.
For critical applications, get either an internal or external controller-based modem. Figure about $100 and up for the external.
ITU 150.1 is the standard for interoperability between modems and other data equipment over IP. (That's separate from Fax-Over IP). If, a BIG if, the provider(s) have implemented it properly, your modems should work.
ITU 150.1