Ntl use 3 different types of Exchanges, depending which company built the network in the first place!! i.e whether it was Nynex, Videotron etc etc. They can be Nortel DMS, Marconi System X or Nokia. The oldest of these would be about 10 years. They can all support Called ID but some require Hardware upgrades to line controllers. The street hardware (multiplexers) are also a problem in some franchise areas, some of this also requires upgrading! NTL seem very reluctant to spend a lot of money on this.
