Quick sort in Silverlight 5

Hi all....

I need help in applying quick sort algorithm in silverlight 5 application.

My requirement -

1. Get all the Mobile numbers in the list box from the database linq-to-sql classes.
 
2. Input a new mobile number in textbox.

3. Check whether the mobile number that the user inputs in the textbox exists or not in the list box using quick sort algorithm

4. I need this quick sort algorithm as there are more than 150 mobile numbers. The sorting and searching time will be reduced.

Please help me out...

Thanks all in advance !!