Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
Melrose Labs SMSC Simulator - SMPP SMSC simulator to test SMS messaging applications.
Ekiga - Ekiga (formely known as GnomeMeeting) is an open source VoIP and video conferencing application for...
Twilio - Brings voice and messaging to your web and mobile applications.
SolarWinds VNQM - VoIP monitoring software
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.