I honestly cannot tell you the bottom line on "locked" versus "un-locked" phones...I can honestly say that I have never had any problems with activation or being able to use the service on ANY nextel handset....if it is a Lost/stolen handset, the activation will pop up an error that will not allow me to use THAT equipment serial number...but if the customer has a secondary IMEI # I can punch into the activation field I can activate the SIM card and that is all we really do.....activate the SIM card. You can put that sim into a compatable handset and if there are not any physical problems with the equipment you can use any Nextel or Boost handset.
As far as I know the only handset that will be locked is a Motorola that is usable on the iDen network but is a registered phone with a company that would be considered a partner to Nextel,such as Nextel Partners or Alltel...these are locked at a "subcity level" straight out of the factory and can only be unlocked by a motorola or authorized service center, and then they to can be used on the Nextel-Boost network...more information than you will ever need, huh?
Later, Jess