VoipReview.com

Texas Instruments VoIP Solutions
B2B manufacturer of VoIP equipment including IP Phones, VoIP Gateways, High Density Gateways, voice-enabled Cable & DSL Modems.
focus.ti.com/

My VoIP Store
Australian-based (Brisbane) VoIP consultant and B2C e-commerce site for VoIP hardware.
www.myvoipstore.com.au/

Asterisk
Open Source telephony switching and private branch exchange (PBX) daemon. Supported signalling protocols: H.323, SIP, MGCP, SCCP (Cisco Skinny).
www.asterisk.org/

Linphone
SIP based web phone. Supported audio codecs are G711, LPC10-15, GSM, and SPEEX.
www.linphone.org/

isdn2h323
Project homepage for isdn2h323, a Linux-based ISDN to H.323 gateway.
www.telos.de/

KPhone
SIP based VoIP phone. It supports Presence and Instant Messaging.
www.wirlab.net/

GNU Bayonne
A free, scalable telecommunications application server by the GNU Project.
www.gnu.org/

GNU oSIP
Implementation of Session Initiation Protocol (SIP). This library provides an interface to initiate and control SIP based sessions.
www.gnu.org/

SIPSet
Sip based phone. You can use it as a soft phone, to make and receive calls from your Linux PC.
www.vovida.org/

Minisip
SIP based phone. Supports video, communication encryption and push-to-talk.
www.minisip.org/