what is a pound key on your phone
Number sign Mainstream use in the United States is as follows: when it prefixes a number, it is read as "number", as in "a #2 pencil" (indicating "a number-two pencil"). The one exception is with the # key on a phone, which is always referred to as the "pound key" or "pound." Thus instructions to dial an extension such as #77 are always read as "pound seven seven."