Open-source Asterisk VoIP software improved

An update to the open-source Asterisk IP telephony platform was released this week, offering better legacy telephony integration as well as improved call-server clustering and voicemail support, the producers of the technology say.

Asterisk is an IP PBX and voicemail software package based on open source software that runs on Linux servers. The latest version (1.2) allows clusters of Asterisk servers to share a single calling plan and end-user database. Also added is support for QSIG - a legacy PBX signaling protocol - and advanced PRI signaling, which allows an Asterisk to interoperate with legacy voice networks.

The new database and clustering features will allow for larger deployments of Asterisk call servers, with better failover and easier management, says Mark Spencer, the creator of Asterisk and president of Digium, which sells and supports systems based on the platform.

“You could do [clustering] in the past, but the new version makes it a lot easier to configure,” Spencer says. “You don’t have to say these phone extensions are on this server, and that that server. Now you just add the extensions, and the whole system becomes aware of the changes.”

QSIG and improved PRI support will allow Asterisk IP PBXs to see Caller ID information from calls sent from a PBX to the Asterisk server. The ability to transfer and tie together calls from legacy PBXs and from the public phone network are also part of the advanced PRI improvement, he adds.

For voicemail, Asterisk already offers Web-enabled mailboxes. But the new version will allow users to distribute voicemail systems across multiple servers and disk storage systems, so that the voicemail storage device - such as a NAS box or simple disk array - does not have to physically sit next to the server running the Asterisk voicemail application.

The open-source IP PBX platform is used in city offices in Manchester, Conn., where 1,500 voice endpoints are attached to an Asterisk system. IP telephony service providers also use the platform to provide VoIP connectivity for consumer and enterprise customers, Spencer says.