I have activated my phone with Virgin Mobile, but I need to switch it to Cricket Wireless.

AT&T and T-Mobile and the cell providers they own (ex: Cricket) use GSM and GSM uses a SIM card.
Sprint and Verizon Wireless use 'CDMA' and they do not use a SIM card.
The first thing you need to know is whether the network you are trying to connect with uses GSM or CDMA.
After that, you'll know whether you need a SIM card or not. If you bought a CDMA phone and want to use a GSM network there is NOTHING you can do about it.
On the other hand, if you want to use a CDMA network then you may still be able to activate your phone. First go to a site to determine if your phone is unlocked such as the one below. After that you can then go to the service providers website and look for instructions how to activate your phone on their network. Note that some providers may force you to buy a phone from them (such as Virgin Mobile) and again, you're out of luck if you haven't.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwjm5N7Wws3XAhVs5IMKHWqyCzMQFggwMAI&url=https%3A%2F%2Fwww.macworld.co.uk%2Fhow-to%2Fiphone%2Fhow-tell-if-iphone-is-locked-or-unlocked-3614824%2F&usg=AOvVaw0bt5gDHHcj_nzJwKrLZE0f

yes you can. You'd have to jailbreak it then unlock.

YOU CAN CONTACT VIRGIN MOBILE (1-888-322-1122) AND THEY CAN ASSIST YOU WITH THE ACTIVATION. WHEN YOU CALL, HAVE THE PHONE OFF AND REMOVE THE BATTERY, YOU MAY NEED TO READ THE NUMBERS LOCATED UNDER WHERE THE BATTERY SITS.

Activation code Pro X5

US Cellular phones each come with unique SPC/MSL codes. To "unlock" it you must find out the SPC/MSL code and change it to all zeros. After you unlock it, you would then need to install a new prl file that corresponds to your new carrier. Only then can you activate new service with another carrier.
There are Windows programs out there that will let you do this (e.g. CDMA Workshop, DFS, QPST, QXDM).
If you use QXDM software, here's a quick link for the commands:
http://cellphone-gur...code-using-QXDM

Virgin is in the USA but I'm not sure if they allow service programmed phones. Metro's big brother Cricket allows flashed phones and they have reasonable prices. As far as your "call not allowed" issue, I would recommend using Metro's Over The Air (OTA) programming method.
Dial *228 for OTA Programming. Hope this helps!

Flash or Flashing--Technically, flashing refers to the overwriting or re-writing of the phone's firmware. There are many phones which can be flashed to cricket with all features working. On most CDMA phones, programming the phone can be done "over the air" by dialing a special code, usually *228 or some variation. Colloquially speaking, flashing can also loosely mean making a phone from one carrier work on another carrier. The easy way to tell the difference is that if your phone does NOT take a SIM card, then it is probably CDMA.

To flash a phone to cricket you will be overwriting th phones firmware. The firmware is software in the phone that doesn't change when you turn it off, and it cannot be deleted unless it is overwritten, hence flashed. It requires specific files called prl files.PRL or PRL File--Short for Preferred Roaming List--A small text file containing instructions for how a phone connects to a specific network's radio towers It is usually loaded by connecting the phone to a computer to overwrite its data. There are a few tools used such as a pst PST--Short for Phone Service Tool or Tools--Special software used by phone manufacturers to program their phones. And also a monster file - -"Monster File"/"Monster Pack", ROM, or "Kitchen"--System software that is needed to flash a phone.

In almost all case you will need to access the phones service programming menu- - -Service Programming Menu--A special menu typically hidden from the primary User Interface that allows for "deep programming" of a phone.You will also need access to msl and spc codes specific to the device you are flashing.MSL/SPC--Special six-digit codes needed to access service programming features on the phone. Access to the service programming menu can be disabled in a phone's firmware.

Depending on your phone, it may require extra steps to unlock or get WAP and MMS working. That is why you need the msl/spc codes to allow deep programming to unlock these features. Not all phones will be capable to access wap or send and receive mms.

Ringtones generally have to be prepaid using a flex bucket. It is best to download ringtones before you flash your phone to cricket since they have a limited selection of ringtones and wallpapers.There are cases were flashed phones will not be able to download ringtones directly from cricket.

The details outlined above will not only work with cricket but you can also flash phones to metro pcs using the information provided above. It is best to do all your research before purchasing your phone to ensure that the cell phone you are interested in can be flashed to cricket or metro PCs

my solution is real easy but in both case u gonna need msl code which u can get it from boost mobile just tell them u bought this phone online and and u need msl code to program it.press ##786# >RTN Menu>Reset>Enter MSL>Ok.
##3282#3G data programing scrol down to restore and put ur msl code and ur problem should be fixed.

you have to get a seperate phone and call customer service and set it up. Or go online @ virginmobileusa.com and activate.

If you would, send me a kickback! :D
email: [email protected]
Kickback code: hTvsPJQD
Hope it Helps!

if you buy any virgin mobile phone the lock code is always the last 4 digits of your cell number if you buy it used from someone then you have to either get the last for digits of their number or take it in to virgin mobile and have then change it for you