Tron MVNO was created in 2010.

They use At&t's network because they are a MVNO or they share their network.

Asda Mobile is a mobile virtual network operator (MVNO) in the UK, operated by Asda, by 2p/min and 2p/text, however is 60p/MB more expensive for Internet use. Asda Mobile does not provide an unlocking service, nor does it supply.

Only GSM Cell phone's operating on the AT&T frequency will work. PureTalk is an AT&T MVNO (mobile virtual network operator) which basically means they are an AT&T service reseller, buying the service in bulk and setting their own fees. Network access/speed wouldn't be compromised because it would still be AT&T.

Straight Talk is an MVNO (Mobile Virtual Network Operator), which means that don't use their own towers - rather they "lease" service from a couple other of the nation's leading service providers.

Tracfone wireless piggybacks on all four of the major carriers, depending on what phone you use.

GSM: AT&T, T-Mobile

CDMA:Verizon,Sprint