In most countries cell phone numbers are not geographical. Instead they have their own unique codes/starting digits used nationwide. This is not the case for: Argentina, Brazil, Canada, Mexico, USA and some Caribbean nations. In these countries you can not tell a cell number from a landline because they all use area codes.
For example, all Australian cell phone numbers start with digit 4, so if you see an Australian number that looks like +61 4 ???? ???? you'll know it's a mobile phone, although there is no way to know its city/region. On the other hand, dialing to Las Vegas, USA (area code 702) from outside the US looks like this: +1 702 ??? ????, regardless of whether it is a landline or cell number you are calling.
Although, as explained above, cell numbers in many parts of the world use their own range of unique national codes, these codes are a part of the cell number. No one will give you an incomplete number if they want to hear from you. So no, don't add any extra codes to a cell number. Just the exit code and the country code and your call should connect.
If you have been given a cell number starting with zero leave it out of your dialing sequence.
For example, this UK number 0700 000 0000 will work when dialed from the UK. From any other country, dial it without the initial zero: +44 700 000 0000.
Use our top navigation to visit the country you want to dial to and you'll find information on what cell phone numbers look like over there for most countries.