Dingtone
Dingtone is a US based telecommunications and VoIP app, which offers services like voice and text messaging, conference calling, Fax and a second phone number. The company was founded in 2012, by Steve Wei and is based in San Jose, CA, US. Dingtone is based on the freeware model, and provides two numbers: one free number and one paid, each registered in different countries such as US, UK, Canada, Australia, France, Germany, Belgium, Netherlands and Poland. Services 
Dingtone offers below services 
 Free calls and text messaging
 Conference calls (with up to 1000 users)
 Fax messaging
 Two phone numbers for users
 Dingtone Credit, virtual currency used in the app. Built-in games

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Android (operating system) software
IOS software
Instant messaging clients
Cross-platform software
Communication software