Product Name: OpenAM (H.323 Answering Machine)
Product URL: http://www.openh323.org/code.html
Vendor: Open Source
Supported Protocols: H.323
Platform: Any platform where you can compile the OpenH323 Library (Linux, Windows, FreeBSD, Solaris, etc.)
Description:

Operational Experience: It can accept multiple connections simultaneously and runs a user defined program after each call, which can be used to automatically send the recorded message as a MIME encoded email attachment to a known email address. If the recorded message is encoded using G.723.1 codec, it requires to equip the PC with additional cards (Quicknet). No dynamic configuration is possible; once the program is started the client is configured using the command line options. Overall Evaluation: Simple answering machine using the H.323 protocol. Really useful in case of unified messaging scenarios. It needs to operate in an environment where supplementary services are implemented. Drawbacks are static configuration and no dynamic management.

Product Name: Yxa
Product URL: http://www.stacken.kth.se/projekt/yxa/
Vendor: Open Source
Supported Protocols: SIP
Platform: Any platform where you can use Erlang programming language (Linux, Windows, FreeBSD, Solaris, etc.)
Description:

Operational Experience: Yxa is a bunch of library like functions for receiving, processing and sending SIP messages, and a couple of small programs that can do various things. The operational experience is poor right now because Yxa is not widely known (even if it is gaining popularity). It is a SIP server open source software written in Erlang (a programming language from Ericsson with open source releases). Basically it has built-in some software for performing a number number of functionalities. One of the main applications is the incomingproxy; it can handle REGISTER requests and authorize different users to make calls to different classes of PSTN numbers, it can proxy requests from UACs to other parts of the Yxa system, relay requests to remote servers/domains Routing features, do ENUM lookups of things that looks like E.164 phone numbers and do lookup addresses in LDAP. Overall Evaluation: The project just produced some nice results. No release has been made yet and downloading is done only through CVS. A mailing list is available for questions and inquiries.