Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
MicroSIP - MicroSIP is a free portable SIP softphone for Windows based on PJSIP stack.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Sipnetic - Sipnetic is a free VoIP softphone based on the SIP protocol.
Facebook Messenger - Facebook Messenger is a faster way to message.