Cell Phone Interference -Data Center.

I have never heard of anyone restricting cell phone usage around computers.
Anything electrical produces EMI; from the florencent lights in the ceiling, fan on your desk, and even your watch on your wrist. And the biggest producer of EMI close to your computer would be the monitor.
The FCC regulates the amount of EMI that devices can produce. I am sure you have noticed the FCC sticker or writing on just about any electronic device. That is why computers have shielding inside of the case.To keep the computer EMI from reaching other devices and at the same time to keep other EMI from reaching the computer.
The most interference you will see from a digital cell phone is an occassional clicking and other strange sounds from the speakers. The reason is because the speaker wires act as an antenna picking up the signal.

Usually the problem is the other way -- cell phones work poorly in computer rooms, mostly because of all the metal in the way, sometimes because of the radio noise put out by older computers.

When you consider the very low power put out by a cellphone, and the emi shielding of most modern computers, I have never heard of it being an issue.

By the way, it CAN BE an issue between certain types of cell phones and certain phone systems. If I bring one particular brand of cell phone within several feet of one of our system speakerphones, I hear a ticking noise in the phone.

Good luck.

From BSI (German Standard)
"There should be a ban on bringing into a computer centre any portable IT systems, mobile phones or cameras unless these are under the control of the organisation concerned. In general the use of mobile phones in computercentres should be forbidden as these can cause considerable interference to the operation of IT systems."

That's their recommendation, I wondered how practical it is and if anyone has pointers to research that definitively points to problems.