Why do some phone numbers have plus in front?

Answer 1

The + is used in international phone numbers. It indicates that the caller should dial the international access code for the country they are dialling from.

For most of Europe and Africa, this is 00. North American uses 011. Other countries may use other numbers.

For example, +44 20 7222 1234 is a number in London, U.K. It would be dialled as 00 44 20 7222 1234 from Germany, or as 011 44 20 7222 1234 from the USA.

Answer 2

When seen at the start of a telephone number, + indicates the need to dial whatever code is used to start an international call in the country being called from.

For example +44 1632 234567 is a British telephone number shown in full international format. So, in this case the person calling would dial their international access code (usually something like 00 or 011) followed by the digits shown.

The + symbol is used because the actual numbers dialled are different in different countries. For example, in most of Europe 00 is dialled to begin an international call. In North America, 011 is used, while Russia requires the caller to dial 8, wait and then dial 10.

Mobile phones usually simplify the process by accepting the + symbol when dialling or storing a number - it's normally entered by holding down or multiple presses of *, 0 or #. The phone will automatically recognise the + symbol as representing an international call and allow it to be called without the user needing to do anything else.