Backwardly compatible with IS-95, this standard allows migration of narrowband cdmaOne networks to 3G. Proposed by the 3GPP2, it has now been adopted as one of the family of IMT-2000 standards. TIA has released 1XRTT (data rate of 144 kbps) and 3XRTT specifications, which are for the initial and later phases of this 3G standard.