Perfect for small installations needing only a small number of lines Digium A4 Series cards support a combination of up to four station or trunk modules for a total of 4 lines.
The A4 Series of VoIP PBX Hardware analog cards supports up to 4 connections for each card in your Asterisk system. Using Digium's single-port interface modules, A4 series cards can scale from 1 to 4 ports.
Digium gives you the exact port configuration you need as the modular nature of the cards allows you to mix and match between FXO (line) and FXS (station) interfaces. Digium A4 Series analog cards are available in low profile, half-length PCI and PCI Express form factors.