Unlocking a Boost Mobile phone is pretty easy, especially if you intned to use it with Sprint or Nextel. Most Boost phones will work with Sprint/Nextel right out of the box, and the same applies for phones made for those phone service providers.
The reason you do not need to unlock the phone to use it on those services is because BM doesn’t own their own cell phone towers or anything, they have an agreement with Nextel to use their network, which is why BM is a MVNO (Mobile Virtual Network Operator). Theirs phones work just like the other two companies phones because they are using the same network.
If your wondering how to unlock a boost mobile phone and intend to use your boost phone with another prepaid service provider your going to be out of luck, using a prepaid phone with another prepaid company is impossible because Virgin Mobile’s phones are custom made with custom programming options that would not be available on any other phone, as Tracfone’s phones are.
The only hope would be using a T-Mobile phone with Boost, or a Boost phone with T-Mobile, but it all depends on what type of phone you have. You will usually need to send the phone in to be professionally unlocked, or find a phone specific hack.
Thanks Brian for asking your question, and I hope I have answered everything you inquired about.

boost uses tdms and gsm phones and tdma phones do not use the same network. Boost is not cricket, it is the old nextel iden system.
tdma, typing error
You can use any phone and activate it through boost mobile as long as it has walkie talkie capability
You CANNOT use any phone and activate it with Boost. It doesn’t matter if it’s PTT (push-to-talk) or what you say “Wallkie Talkie”. When you activate a phone with Boost, you will have to enter the IMEI (or tell the CSR). That IMEI will be compared to a database located at NMS (Number Management Systems). And how does this “database” get built? Motorolla or Sanyo or Blackberry sends a file to the NMS system periodically that basically says, “Hey NMS, we just shipped these phones to the stores.” NMS then loads that file to the database. Therefore, if you didn’t buy the phone at the store (stole it, black market, etc.), the IMEI will not be in the NMS database and you will not pass the validation check.
By the way, the IMEI validation is step #1 in the activation process.
How do I know this? I’m a Boost employee and my job is to identify and fix the cheats you hackers try to do.