Well, this is for VerizonWireless...so, I don't know if it will work for you.
But when you change your number the internet access will also need to change.
Settings > Connections > Connections...
Click the Advanced tab
Click the Select Networks button
Click the Edit button
Click the Edit button
Click the Next
Click the Next
------remember this is for Verizon Wireless------
User Name should be:
##########@vzw3g.com <----The # is your phone number. This is the part that might need to change.
PW: vzw
Domain: <blank>
Click Finish
Hope this helps.