Lucent/Avaya offered 2 types of software at one time,, BSC ( category "B") and ECS ( category A ),, the ECS system was a more expensive system to buy because of all the extra networking features that you got with the basic package, so it ran the Tn2224's Tn793's and Tn464's,, allot of customers did not need all of the features of the ECS so they had to come up with a less expensive system so the stripped down the software and made the BCS and when they did that they came out with the Tn2214, Tn2793, and the 2464,, which are all the same cards but they were also cheaper in price, price was the whole driving factor for this move,,, you can use the Tn cards out of the ECS in the BSC software switch but you can not use the BCS Tn cards in the ECS system,, this kept customers from buying a ECS system with all of the features and the buying the cheaper Tn cards,, just as an example,, when these system came out the ECS basic cabinet and common cards with RTU was about 15K and the 2224, 793 and 464 were 1800-2400 each,, then the BCS came out the cabinet and commons cards was 5K and the station cards were 1400-1600 each