why in front of my phone number iPhone

+ in a phone number represents whatever dialing code you need to invoke international direct dialing.
This is followed by the country code, and then phone number, usually dropping what ever code distinguishes national from local numbers. My number in the UK is 020 7... which becomes +44 20 7...
tt2
Various PCs Windows XP Pro iPhone3GS iOS4.2.1, 160Gb 1.1.2/2.0.4, 30Gb 1.3, Nano 1.4 - iTunes 10.1.2.17

sorry, i dont understand. mine just has the normal 1-areacode-phone number. no country code or anything. and the + in front of the one, no country code.
MACBOOK PRO 13 MID 10 Mac OS X (10.6.5) iPhone 4 / iPod touch 4g