Linphone - Linphone is an internet phone or Voice Over IP phone (VoIP).
ReadingIQ - ReadingIQ is the most leading digital learning library app for kids ages 2 to 13.
Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
Preschool - Preschool!
Sipdroid - Free and open-source SIP/VoIP Client
Bini Super ABC - Bini Super ABC! Alphabet Games for Toddlers and Kids is a fun education app for those kids who want to learn letters and sounds of the whole alphabets.