Locked, Blocked, Black Listed Cell Phones

What does it mean for a GSM mobile device to be unlocked? What sort of locks are there? How is that different from Blocked? What is a Barred or Banned or Blacklisted cell phone? That is what this guide will look at.
Blacklisted -
If you phone is lost or stolen you can report the International Mobile Equipment Identifier (IMEI) to your carrier. They will broadcast that number throughout their network and make it impossible for the phone to connect to make a call. This known as blacklisting the phone. This is sometimes called a barred or banned device. In some areas the various carriers share the IMEI numbers of lost and stolen devices making it impossible to use the device on any carrier. In some countries this sharing is a requirement of law.
A blacklisted phone should be returned to the owner. This can be done bydropping it off to the carrier branded on the phone. Then it is up to them to return it to the subscriber. You can check with your carrier prior to purchase to see if a phone will activate on that carrier. You will need the IMEI from the seller, then you are a phone call away from knowing if you are about to buy a lost or stolen lightweight desk ornament.
Blocked Cell Phone -
Ifthere is an outstanding balance on the billsome carrierswill blockthe device from being used until the bill is paid. Some carriers tiethe balance to the device. This is not gemon with GSM carriers but is frequently the case with CDMA and TDMA carriers. If you purchase a blocked device you will need to pay the balance to get it running again -if they will let you. The privacy policy of some carriers will prohibit third party payers for past due bills. Some carriers block the device forever and some for six months. A call to your carrierto check out the IMEI or Equipment Serial Number (ESN) will allow you to avoid purchasing a worthless device.
Blocked SIM -
TheSubscriber Identity Module (SIM) identifies the subscriber to the network through the International Mobile Subscriber Identity (IMSI). This allows you to move your SIM from device to device and have your carrier recognize who you are.
You can set your device to requirea Personal Identity Number (PIN) to access the SIM.(seeSecurity Lock below)If you enter the PIN incorrectly too many times the SIM will lock and you will need to get a Personal UnlockKey (PUK)from your carrier to gain access to the SIM. Enter the PUK incorrectly too many times and you will end up with the need for a new SIM. Messages vary bymanufacturer as shown:
Make PUK Required New SIM RequiredAlcatel 3 Bad Codes! PUK CodePlease call operatorMotorola BlockedBlocked - See SupplierNEC This SIM is blockedUnusable SIMNokia Simcard blocked - Enter PUK Simcard rejectedPhilips Enter PUKPIN blocked (May say SIM blockedSamsung Please enter PUK Code Contact service providerSharpPin Blocked Enter PUKPUK BlockedSony Ericcson Pin blocked - Unblock? Blocked - Contact your Card Provider
Locked -
Service Provider Lock:
Most GSM devices are sold to be used with on a specific GSM carrier such as T-Mobile, Vodafone, Cingular, Rogers, Fido, TiM, etc. The device will accept only a SIM from the GSMcarrier that sold the device. This is known as a Service Provider Lock (SP lock). You will know if you have a SP locked device if you receive one of a variety of message at startup such as "Subsidy Password","Phone Restricted","Insert correct SIM card", etc. and the phone does not budge until you enter the code or put the appropriately branded SIM in place. The SP Lockis also, less precisely,called a SIM lock.
Hard Lock:
Entering the unlock code incorrectly too many times will result in the condition known as hard lock. This requires theuse of a piece of hardware to remove the Service Provider Lock and to reset the code entry counter to zero. The hardware can be a stand-alone itemknown as a clip or it may be a geputer with unlocking software and a cable connecting your device to the geputer.
Security Lock:
The end user of a devicecan provide that a password be entered to allow access to the SIM. Since the IMSI information is on the SIM this effectively prevents unauthorised connection to the network. This properly is called a Security Lock. The password is known as the Personal Identity Number (PIN). This is also known, less precisely, as a SIM lock.
Network Lock:
Devices may be locked to a particular network. For example 310-260 isa network code for T-Mobile in the USA. In Germanythe T-Mobile network codeis 206-01. The network lockwould allow T-Mobile to prevent a user from using the T-Mobile USA device on the T-Mobile Germany network and vice-versa. The Network Lock is also one of the most frequently implemented locks. AT