Provides a cross-platform, open source softphone. Includes a mailing-list and a wiki.

Provides SIP client software, server software, and software development kits.

Provides SIP products and applications for service providers and enterprise networks.

Provides a software development kit for adding SIP calling features to applications.

Provides SIP softphones for service providers, integrated with Microsoft's UC platform, IBM's Lotus Notes and Sametime.

Provides a SIP softphone and a SIP-compatible audio codec.

Provides SIP softphone, web-to-phone, and click-to-call software.

Offers SIP softphone freeware for Windows. English and German instructions.

Provides a SIP softphone with switchboard for receptionists.