Cellphone Services Brace for New Era.

Reports that cellphone users will be allowed to keep their phone numbers, called "number portability," even when they switch service providers. Number of cellphone users in the U.S., suggesting that this is a big change in the way cellphone service companies will work to retain customers; Percentage of wireless customers that switch providers yearly; Promotional tools being offered by providers to retain customers; Deals being offered by Deutsche Telekom's T-Mobile USA Inc., Sprint PCS and AT&T Wireless Services Inc. to retain customers.