Cant add a Zero infront of mobile numbers

Hi. Hoping someone can advise me with this as I am not an expert in Excel.
My roblem is that I have a number of colums which one of the is for phone numbers, but when I try to add a mobile number, it wont let me put a 0 at the start of the number. Once I click out of the cell, the 0 just vanishes.
What do I have to do so that it will accept zero's.

Thanks everyone for your help.
Cheers

Hi,

Format Cells Text ...
and then add your 0's ...

HTH
Carim

Thx for the advise Carim.
Works fine now.
Thx again
Regards