Speex is a patent-free compression format designed especially for speech. It is specialized for voice communications at low bit-rates in the 2-45 kbps range. Possible applications include Voice over IP (VoIP), Internet audio streaming, audio books, and archiving of speech data (e.g. voice mail).
The SIP Switch is a Web application which allows you to use multiple SIP accounts on the same phone. This lets you use the call plans of different VoIP companies (using SIP) with one IP phone device. It does the third party SIP registration so you can receive all your calls on the sipswitch account. On dial out, you can set prefixes to make your outgoing calls with such or such provider.