Why is there a plus sign in front of phone numbers?

The plus sign (+) in front of a phone number is known as the international dialing prefix. It is used to indicate that you need to dial the international access code for the country from which you are making the call before dialing the rest of the phone number.

When you see a phone number written with a plus sign, it's a shorthand way of indicating that you should replace the plus sign with the appropriate international dialing prefix for the country you are calling from. The international dialing prefix varies by country, and it is used to initiate an international call.

For example, if you see a phone number written as "+1 555-123-4567," the plus sign indicates that you need to dial the international access code for your country, and for the United States, that code is "011." So, you would dial "011 1 555-123-4567" to make the call. The plus sign is a standardized symbol used globally to represent the international dialing process.