A free program for Android, by Voice Services.

Customers can switch from traditional “fixed” lines to their current smartphone without giving up any of the extensive capabilities they have grown accustomed to from their current phone system thanks to Secure VoIP.

You only need:- An Android smartphone- Internet accessibility- A headset for the highest quality audio- A VoIP service.

VoIP security advantages:- Simple to use- Without fee- Easy and Quick Installation- Manage all of your call settings directly from the app.- Cloud PBX capabilities- High Definition Video Conferencing and Calling- Secure; TLS support- Support for dynamic adaptive call quality in the Opus codec- High Definition Wideband Video and Voice (Opus & G.722) (H.264)- Call transfers, three-way calling, and conferencing- Speakerphone, Mute, and Integration with Contact Lists- Background operation support for push notifications