What does a + sign at the beginning of a telephone number mean?

Question

I've been getting a call on my cell phone for the past 2 days and I have no idea what it is. It begins with a + sign and then it has 11 numbers (beginning with 506). I don't have international on my phone....

Answer 1

I guess it means 00

Answer 2

It typically means it is that you are getting an international phone call ...  

Answer 3

The "+" sign  precedes the country-code for an international number. So, "+506" would be the country-code for Costa Rica. Costa Rica uses 8-digits for their telephone numbers and they don't use city-codes, nor area-codes like N. America.

So the number +506 xxxx-xxxx is a call from Costa Rica from the telephone number xxxx-xxxx.