RMDialer

RM Dailer is a free SIP softphone dialer app intended to make VoIP calls over the Internet. It comprises of a handy user interface that makes it easy to use for the non-techies. The call quality it provides is smooth, clear and crisp. The end-users of RM Dailer include business, call centers, service providers, or any entity that is in need of constant communication.

Note:

RM Dailer does not come with any VoIP services and operates alone as a client-side software. Users need to subscribe VoIP services from a provider to make calls from it.
RM Dailers's key features include:

 Secure, SIP-based softphone
 Premium audio quality, ensuring crisp calls
 Predefined VoIP available when adding new accounts
 Multitasking support for background operation, such as fielding incoming calls while using other applications
 HD audio codecs, such as OPUS, SILK and G.722.
 Support calling accessories, such as headsets and headphones. Android app users can have Bluetooth support too.

STANDARD PHONE FEATURES
 Multiple account support on SIP-compliant server
 Call history of all calls; received, missed & dialed calls
 Call display and voicemail feature
 Contact List comprising of all the native contacts
 Call hold, mute, speakerphone options
 Call recording
 Dial plan support
 HD Audio codecs
 VPN support
 Security and encryption