Bria is described as 'Thoughtfully designed, Bria 5 leverages over 10 years of softphone experience in improving productivity for our customers. Stay in your tool of choice and still have access to the power of Bria. Feel like you are in the same room regardless of where you are' and is an app in the Social & Communications category. There are more than 10 alternatives to Bria for a variety of platforms, including Windows, Mac, Android, iPhone and Linux. The best alternative is Jitsi, which is both free and Open Source. Other great apps like Bria are Jami (Free, Open Source), Linphone (Free, Open Source), LINE (Freemium) and MicroSIP (Free, Open Source).
Jitsi (previously SIP Communicator) is an audio/video and chat communicator with full encryption that supports protocols such as SIP, XMPP/Jabber, ICQ/AIM, Windows Live, Yahoo!, GTalk/Hangouts extensions, as well as OTR, ZRTP, etc.
Jami (formerly GNU Ring, SFLphone) positions itself as a potential free Skype replacement Open Source and cross-platform. Jami gives you a full control over your communications and an unmatched level of privacy.
Linphone is one of the most famous open source softphones in the world. It is fully SIP-based, for all calling, presence and IM features. Use Linphone for free, and enjoy its intuitive interface and advanced features with our free SIP service or with an existing SIP account.
LINE is a Japanese proprietary application for instant messaging on smartphones and PCs. Line users exchange text messages, graphics, video and audio media, make free VoIP calls, and hold free audio or video conferences.
Telephone allows you to make phone calls over the Internet or your company network. If your phone line supports SIP protocol, you can use it on your Mac instead of a physical phone anywhere you have a decent network connection.