Excel function to Check neighbour cells match for all

Hi,

I need to check if (each) cell in column A is having a match in column B, Example as below:

Column A is phone numbers list, column B is messages list ( which will contain a text and one phone number "it should be the same phone number as the one on column A") Now i need to make sure that phone number on A1 is the same phone number that occure on B1,etc. I dont know how to check if A1 phone number is the same phone number on B1 ? or not, and apply the check for all cells in the column? it should show me only if it is not the same.

Many thanks in advance.