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Историческую версию Crystal можно получить на Android
Crystal dialer - это приложение для мобильного VoIP-звонка
Features :-
Crystal dialer uses SIP protocol based for signalling.
Supports G729 codec.
Runs Behind NAT or private IP.
User Friendly Interface.
Auto Sync of Balance.
Real Time Sip status messages.
Call History.
Address book integration.
Compatible with all sip standard switches.
It has very efficient implementation of jitter buffer to play voice smoothly.
Silent suppression and comfort noise generation has been used to reduce the bandwidth usage, and this makes the dialer more efficient in making VoIP calls.
Integrates with mobiles phonebook.