Digium's TE420B PCI Express card provides termination of up to 120 channels of voice or data across four E1, T1, or J1 interfaces in a PCIe x1 form factor. Selectable on a per-port or per-card basis, the TE420B allows E1 and T1 circuits to be mixed with full channel synchronization. Supporting PCIe x1, the TE420B may be used in any available PCIe 1.0 compliant slot - 1x, x4, x8, and x16 without considerations for voltage selection or lane size.

Digium's VPMOCT128 Octasic DSP-based echo cancellation module provides the G.168 algorithm which has been labeled a benchmark for echo cancellation and performs 128ms (1024 taps) of echo cancellation across all 128 channels in E1 mode or all 96 channels in T1/J1 modes.

The TE420B supports industry standard telephony protocols including North American and European Primary Rate signalling as well as standard Robbed Bit, Channel Associated Signalling in addition to standard PPP, HDLC, and Frame Relay data modes.