Cellular phones are different from your land-line home phone in that youll need to determine in advance how many minutes youll use in any given month. Deciding how many minutes youll need and making sure you dont go over your allotted minutes is one of the trickiest parts of using a cellular phone.

The most common arrangement for cellular phones is a block minute plan. With a block minute plan, youll pay a flat fee to purchase as set number of minutes each month. The disadvantage of this plan is that if you purchase 200 minutes per month, youll be billed the same amount whether you actually talked for 199 minutes or 60 minutes.

Something that many new cellular phone users dont realize is that youll also be charged to receive calls. If youre worried about going over your allotted minutes, its best not to give out your phone number to any more people than absolutely necessary.

Like a prepaid calling card, all calls made on a block minute plan are rounded up to the nearest minute. If you call a friend and listen to a 30-second answering machine message, youll be billed for one full minute. Youll also be charged for one full minute if theres a busy signal or no answer, although some block minute plans will only bill you if you let the phone ring more than three times.

With a block minute plan, going over your allotted minutes can quickly get expensive. Youll be charge a penalty rate for every additional minute you use. If youre not careful, this can quickly add up to hundreds of dollars a month in unnecessary charges. The best defense is to buy more minutes than you think youll actually need and reduce your plan at a later date if necessary.