Sipdroid - Free and open-source SIP/VoIP Client
CSipSimple - CSipSimple is a SIP application for android devices.
XO Hosted PBX - Hosted PBX is a scalable UC solution that uses cloud technology to integrate HD voice & data services, mobility, along with advanced calling
Linphone - Linphone is an internet phone or Voice Over IP phone (VoIP).
HoduPBX - Communication with your team streamlined. Simple & easy!
Handy News Reader - Handy News Reader is a free no-ads RSS reader for reading offline contents from RSS feeds or web sites without RSS feeds.