The term "subsidy" refers to the subsidization of cell phones sold to customers that purchase mobile phones as part of a contract with the mobile service operator. Many network operators provide these subsidies as an incentive for users to sign extended contracts, and use the
subsidy lock as a means of protecting their investment. The installation of such locks means that users often are forced to purchase a different phone if they decide to switch their network (of advantage to both the OEM manufacturer and cellular service provider). CDMA cellular providers that use subsidy locks on their handsets: Ntelos, Cricket, Sprint, Quest, Philippines Cellular, SureWest, Telus & Bell Mobility (Not a complete list) GSM: (SIM unlock) globe smart sun Alltel or Verizon Wireless do not use any type of subsidy locks on their CDMA phones. Default Code:000000 or 123456 or 654321 Prepaid cellphones from Alltel & Verizon Wireless come locked from the store, but Verizon Wireless prepaid cellphones can be unlocked with a call to Verizon. ==Unlocking services and software==