Tbh I wonder what activating a phone means.
Transmitted from my Nexus Prime
With GSM phones, your account information is stored in the SIM chip. Take the SIM chip and put it in another GSM phone and the phone assumes the identity/number of the account on the SIM chip.
With CDMA phones, the account information is associated with the phone itself, but that association must be set up by the carrier before you can use the phone with your account. When you get a CDMA phone, you must either call the carrier or visit one of their stores and have a customer service representative update your account information (and the carrier's phone database) with the association between your account and that particular phone. Each CDMA phone has a unique serial number, which is maintained in a database by each carrier for the phones that they sell/allow on their network. If the unique serial number is not in a particular carrier's database, then they will not allow the phone to work on their network (except for calls to 911 emergency).
That is the process of "activating" a CDMA phone.
The original premise behind this scheme was that it was supposed to be more "secure" than the GSM method of using SIM cards. In reality, it only serves as a barrier to customers taking their phone from one carrier to another (since the carrier "owns" the serial number of a CDMA phone, and another carrier won't activate a phone whose serial number doesn't belong to them). So unlike GSM phones, which you can take from carrier to carrier (unless they are SIM-locked), CDMA phones are locked by their nature to the carrier that sold it. If a phone is reported stolen, the carriers flag the serial number of the phone, and won't re-activate it under another account. Thus, the phone becomes "useless".