Iterate Through Numbers And Form A Loop

i have an sms phone book that allows users to send multiple sms from the internet to a cell phone.

However when a users chooses to send bulk, it inserts the numbers into a textfield box seperated by commas. Which are in turn passed to the server side to be sent.

PROBLEM
Now i would want to seperate each number and loop through them e.g

numbers could be : Note they are seperated by comma

2865843275,253245234,254235432,4325432542,2452345234

1. on the server side i would like to loop though each number and assign to a variable

2. Count the number of phone numbers and assign a variable total_numbers to it.

e.g. something like this

for each
a = phone_variable
next

HOw do i achieve this ?