The choice in cellphone carriers is an important decision.   

Calling Areas
It is important to check your cell phone plan so that you know the extent of your calling area.  While some plans allow for national or even international access, other carriers are regionally located or have a rather scattered network.   Traveling outside of the calling areas, means your carrier of choice has to relay the signal through a competitors network, which means additional charges.   They will make up for the added expense and then some by charging you high fees for this service.  

Carriers are both co-operative and rivals, they would much prefer that you stay within their network and this will show in their calling plan.    Typically the plan will have a section on roaming charges, while these aren't as significant as they once were in terms of cost, it is still important to be aware of.    Some carriers may not have the necessary contractual agreements in place and may have areas where coverage is completely impossible, examining the coverage map which your carrier provides can give you insight into potential issues.

Your lifestyle is an important selection in your selection of carriers.    If you tend to travel a lot then you have different needs than if you seldom leave your immediate neighborhood.  Think about how much time you spend driving or Traveling by other means and how far you tend to go from your home.    If you receive calls at work, the entire area of your commute should fall within your carriers calling zone.

Reception
Technological infrastructure between carriers varies considerably.   The amount of bandwidth each carrier can handle depends on their infrastructure investment.   It is a good idea to know what areas have cellphone repeaters and what your carriers reputation in your area is.   You should talk to your friend about your carrier plans, ask them what phone service they are using.  

The difference is most frequently seen when indoors, where reception often has dead-spots.   The cell signal has to travel through the walls to your phone which weakens the signal.    Carriers that have more infrastructure in your area are more likely to have a cell tower or repeater nearby.  The proximity of the nearest signal booster will have a huge impact on where your phone works best.   Some networks are very well developed and others have areas of weakness in their coverage net.   If you tend to hang out in locations where some people have strong connections and others have to go outside or move nearer to the entrance to catch a call, it is a good time to find out who is using which carrier service.

Calling Plans
In an urban area, typically several carriers are competing for your business.   This is generally a good thing.  While it makes the decision of which carrier to use, it also tends to keep your communications costs more reasonable.

As competition has increased, so has the attractiveness of various plans.   Some plans allow you decreased rates during evenings, weekends, or when calling a select group of people.   Others give significant discounts to people on the same cell phone network.    If all of your friends are using a carrier plan, you should consider getting the same service, simply for this reason.

Bandwidth
As cellular usage has increased, the amount of bandwidth the phone carriers have to provide service has increased to accommodate the demand.   Modern phones and communication devices can now handle the bandwidth intensive demands of internet.   Applications such as the blackberry and the I-phone have been specifically engineered to take advantage of this capacity.    Internet service plans may vary between carriers.   If you plan on doing a lot of networking while away from home, this can be a consideration.

Minutes
Plans have greatly expanded the number of minutes that carriers are willing to give to their plan subscribers.    As a customer the explosion of cellphone usage works to your benefit.   Intense competition and infrastructure improvements have given rise to higher expectations of service provided by carriers and a demand for reduced costs.     Plans are commonly available to provide hours of talk time, or even unlimited communications for a flat rate.  

Only a few years ago, cellphone minutes were a huge issue.    Now, plans offered by cellphone service providers are vastly improved.   Overage charges used to be applied by carriers after a couple hundred minutes, now plans offer thousands of minutes or more of talk time.

Nonetheless, it is still important to be aware of your carriers plans.   Opting for the budget plan can be tempting, but if you spend an unexpectedly large period of time communicating on your phone, overage charges can be extreme.   Many subscribers opt for plans which give them maximum flexibility and overall strong rates.  

Nights and Weekends
Many carriers offer a discount for calling during off peak business usage cycles when their networks are experiencing a lower level of bandwidth demand.    These savings can be significant, although they vary with the plan.   It is important to have an idea as to when you tend to use the phone.   If you find that most of your communications are business related, a plan of this nature may not be as suitable as one which offers good overall rates.    Of course if you work evenings or just use your phone when you are chilling at home after work, carrier plans which offer this type of rate can be particularly attractive.

Customer Service
Carriers have different reputations for customer service.  This may vary from region to region.   If you have recently moved to a new area and need to select a calling plan, pay attention to what plans people are using.   Comment on their phone, this can often create an opening to discuss any service issues or other factors that you may wish to consider.   Many people have tried different carriers and may have strong feelings about why one is better than the other.   After speaking with a few people you should have a much better idea about which carriers service you should request.

Phone carriers

Selecting a phone carrier is not as important as selecting your friends, but having them in reach and the budget left over for activities is important.   Choose the right carrier and your life can be much easier whether you are mobile or just like a good phone deal.   Always check the plans which your local carriers offer and find the plan which best suits your calling patterns.