ITU Standard V.90 is the official designator for the ITU draft recommendation for 56K modems. V.90 is the official standard and has been approved by the ITU members at the end of 1999. Lucent was one of the leading contributors to the V.90 specification. Interoperability V.90 will finally allow you to connect to any ISP that has V.90 interoperable modems.
Interoperability is a key factor that enables different modem brands to connect.
Lucent based V.90 modems will continue to support K56flex, so if your ISP has not yet upgraded, you can still get a high-speed Internet connection. Not all modems are capable of supporting both K56flex and V.90. Just look for the Lucent Technologies logo to make certain. The majority of client modem manufactures and head-end Internet equipment manufacturers have made the V.90 software upgrade available to their customers as soon as it became available. As the ISPs upgrade their equipment to V.90, K56flex has played an important role during this transition.