Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
Smooch.io for WhatsApp - Engage with your customers on WhatsApp like never before
MicroSIP - MicroSIP is a free portable SIP softphone for Windows based on PJSIP stack.
WhatsApp for LiveChat - Let your customers reach you via Whatsapp
Sipnetic - Sipnetic is a free VoIP softphone based on the SIP protocol.
EfficientChat - EfficientChat is a completely functional CRM & customer operation API based on WhatsApp.