I've done this several different ways in the past, depending on your take of "Cell phone". For the phone that is probably in your pocket right now I've used one of those bluetooth bridges that looks like a bluetooth handsfree device to the phone but on your side you get a 48/90v POTS RJ11 for a regular phone. You can attach a modem to them but some of those adapters do not emit a dial tone. These older adapters have major problems regarding audio quality and noise cancellation. I could not relaibly make it hold a connection above 300bps. Even 110bps had spurious corruption from time to time so barely enough for a teletype connection and over an acoustic coupler it was not a lot better by using one of those hipster handsets that plugged into the headphone jack on phones, when a headphone jack was still a thing......That feels weird to even say. I do have a data kit for motorola's line of bag and car phones but that requires the discontinued AMPS service. Same goes for the data kit for my Tandy rebranded Nokia portable telephone which has basically an audio breakout so you can attach an acoustic coupler. Radio Shack's catalog made this adapter seem WAY cooler than it really was but I guess if you were high-rollin' with a Tandy portable that was one way to dial into the office. On the other hand I've also done data calls over an MSAT phone. A Mitsubishi OmniQuest ST251 if you plug a terminal into the serial port responds to hayes AT commands and emulates a 1200bps modem but the cal was very, very expensive as it switches the radio specifically into a data-only mode. If we're talking satellite phones that fot in your pocket I've logged into Slashnet over a Globalstar GSP-1600 while camping which also appears as a Hayes modem but under Windows you get an extra-special modem definition driver that lets you engage speeds up to a blazing fast 9600bps. -John