On my phone my number looks something like +19172222222 but I think people from different countries have their own codes right? Should I leave out the + and 1 when handing them my number so they don't get confused? Is different when people dial me from foreign mobiles as oppose to landlines? In what form should I give my number?
+1 917-222-2222 is the best form. You may use spaces instead of the hyphens. The form is:
- First group: a plus sign followed by your region's international calling code.
- Second group: your area code (which locals would know to omit).
- The rest: what everyone needs to type.
The important part for international callers is to have the country prefix first, starting with the
+ symbol. Residents of your country or region should know to drop the international prefix and dial their country's long distance prefix instead — but in North America the two are the same.
For, say, a UK number, you would write +44 123-456-7890, where 44 is the international prefix for the UK, 123 is the area code (of variable length in the UK) and the rest is the local number. UK locals would know to dial 01234567890 (0 being the long distance prefix), and locals of the 123 area would know to dial 4567890. If you want to make sure nationals aren't confused about the international prefix, you can present your number in two ways:
UK national: (0123) 456 7890
International: +44 123 456 7890
The form you've written is the least confusing.
+1 is the country code for the US and 917 is your area code in NYC, but leaving them out accomplishes nothing. Locals will know which ones they can drop (actually, in your case none, because NYC uses 10 digit dialing to increase available numbers).
It is impossible to screw up a phone number by providing too much information.
As others have said, a number with a “+” in front is probably the best form and should always work (certainly on mobile phones).
Many people will have numbers in their directories that might not work outside of their home country like “01528889” or “0678294000” (those would be valid numbers in the Netherlands for example) or “0033145900087” (this is a valid French number, with country code, as dialed on a Dutch phone but “00” might not work everywhere). Those are the ones that need to be modified to avoid confusing people.