The first way to find a friend's phonee number might be using a social network. You friend can have an account in one the most popular social networking sites such as MySpace, Bebo or possibly Facebook. In such case finding or contacting your old mate should be effortless - if you friend decided to show his phonee number publicly on his profile, you can get it within seconds. However, if he decided to keep it private, you will need to contact him to get his phonee number. This shouldn't be very bothering, but your friend will surely notice that you for some reason have lost his phonee number.
This may be even stupid to mention but seems to be the easiest way to obtain a friend's phonee number. Of course there are some situations when you want your friend to know that you are looking for his/her phone number. In such cases, you should pick other solution.
You can try to type your friend's name into a search engine and check if there are results with your friend's name. If you find some, you just need to see if he/she published her personal phonee number. This is very probable when she works as a single professional, if she is employed in some company, you will be possibly able to view the work phonee number.
Reverse Phone Lookup
You may have heard of reverse phonee lookups which are used to obtain a name, address and some other details about the given phonee number. But there are not many people who know, that you can make us of them to find a phonee number by a person's name. It works the same way as with the ordinary phonee lookup. You just type in the full name of the person and wait a few moments for results. The result can include residential phonees as well as cell phonee numbers. Opposite to other methods mentioned in the article, this solution is not free, but the price you have to pay for this service is very low in comparison to the quality of the results provided.