How can I unlock my phone to all network providers

Who is your service provider? Are you still in a contract with the service provider?

Where do you live? Call your service provider and tell them to unlock your phone. In their USA service providers unlock the phone

Phones operate on two formats in the US, GSM and CDMA. Verizon network is the only CDMA. All others are GSM.

To run on any network, the phone must be GSM & CDMA capable. CDMA capable phones are usually also GSM capable, but not the other way round. Phones are locked to a network when they are purchased under a CONTRACT. When the contract is over, you can request the provider to unlock your phone.

The phone will then be able to be connected to any provider or to just GSM networks depending on the phone capabilities.