astrtr is a FreePBX module for Asterisk to route calls from one trunk to another. Makes Asterisk PBX a VoIP Switch as well. Includes multiple routing tables, max connections per trunks, some reports, CDRs, etc.
Bluel VMail is a semi-complete Linux-based autoattendant and voicemail system designed to work with the Diamond SupraExpress ISA modem and an outdated (i.e. cheap) Panasonic hybrid phone switch. Uses Perl and vgetty.