Should I add a 1 before the area code in the contacts database

[Aquadoc]

I just got my iPhone 4s and am entering phone numbers manually. Should I add the 1 prefix before the area code or just enter the area code and the 7 digit phone number?  Any help will be appreciated.

[Tidbits]

I just have the 10digit number(XXX-XXX-XXXX) for all my contacts.  You won't have a problem dialing out when traveling and the 1 is pretty pointless to have.

[Aquadoc]

Thanks, I will make the necessary changes to my contact list and see how things work.  I really do appreciate your prompt reply..  I must admit that I noted no problems with the numbers without the prefix so you are most probably correct.