Abto multi account sip dialer

ABTO Software's VoIP SIP softphone. Can be used to call sip numbers and landline numbers (if sip provider has this option). Features: voice calls; video calls; text chat (based on SIP MESSAGE request); works with all popular SIP servers, including Asterisk/FreeSwitch; make direct calls between clients without SIP server; allows to use UDP/TCP/TLS protocols for SIP transport; ability to make secure calls using SRTP; supports STUN/ICE; IPv6 support; CallKit - native incoming call UI and system integration of VoIP calls; 2 simultaneous calls; call conferencing; attended transfer; 4 concurrent accounts.