I have been told that once a Blackberry's EMEI and PIN have been registered with Blackberry for push email on one network provider that this cannot be changed if you use the phone with a different provider, resulting in the loss of the email facillity. Please could anyone out there confirm whether this is correct or not.
Many thanks.

Wirelessly posted (mindlessly posted)

Not correct!
I am using a TMO 8800 on my ATT acct and it was previouslt attached to a TMO BIS acct

However the PIN/ IMEI need to be released or removed from the old service