The X400M FXO module allows the TDM2400P card to terminate four analog telephone lines (POTS) per module. Because of the modular design, a user can activate additional ports at any time with more X400M daughter cards. The X400M module passes all the call features any standard analog telephone line will support. The TDM2400P takes the place of an expensive channel bank and brings the system price point to a low level. By using X400M and S400M modules with the TDM2400P, one can create a solution with support for a range of telephones. To scale this solution, simply add additional TDM2400P cards populated with modules. The naming convention for the TDM2400 bundles is as follows: TDM24 X Y B TDM24. "TDM24" denotes that the card is TDM2400P, "X" denotes the number of FXS modules, "Y" denotes the number of FXO modules, and "B" indicates that this product is a bundle without Echo Cancellation. "E" indicates that this product is a bundle with Echo Cancellation.