ANDROID 


CSipSimple

https://play.google.com/store/apps/details?id=com.csipsimple


Linphone

https://play.google.com/store/apps/details?id=org.linphone


Grandstream Wave

https://play.google.com/store/apps/details?id=com.grandstream.wave&hl=en


Sipdroid

https://play.google.com/store/apps/details?id=org.sipdroid.sipua


Zoiper IAX SIP VOIP Softphone

https://play.google.com/store/apps/details?id=com.zoiper.android.app&hl=en


iOS


Linphone

https://itunes.apple.com/us/app/linphone/id360065638?mt=8&ign-mpt=uo%3D4


Zoiper Premium SIP softphone - VoIP & video calls

https://itunes.apple.com/us/app/zoiper-premium-sip-softphone-voip-video-calls/id787863350?mt=8&ign-mpt=uo%3D4


Media5-fone SIP VoIP Softphone

https://itunes.apple.com/us/app/media5-fone-sip-voip-softphone/id353988698?mt=8&ign-mpt=uo%3D4


Zoiper SIP softphone - VoIP & video calls - Free

https://itunes.apple.com/us/app/zoiper-sip-softphone-voip-video-calls/id438949960?mt=8&ign-mpt=uo%3D4