Many people in the civilized world carry mobile phones and the percentage of cell phone owners rises steeply in Silicon Valley.
There are many networks to choose from, the most popular being AT&T, Verizon and Sprint. Most services require you to take out a two-year contract with an attractive phone price and varying costs for service depending on the type of plan you want. Shop around, ask around, sometimes your company will have a special deal with one particular supplier.
There are many different plans for your home phone as well, depending on what you require. You cannot just pick up your phone and make an international call - you will have had to take out a contract with a long-distance service beforehand, such as AT&T or Sprint. They will usually bill you monthly.
American telephone numbers are made up of a 3-digit area code, a 3-digit exchange code and a 4-digit subscriber number. Your area code will cover a large area, but when making a call to another area (which will have a different area code) you have to dial 1 first then the area code followed by the 7-digit number. For example, to call California Concierges, based in Sunnyvale, from Sunnyvale, you would call 739 3987. However, if you were going to call California Concierges from San Francisco, you would call 1 408 739 3987.