NextPlane - NextPlane offers cloud-based, scalable unified communications federation service for the enterprise.
Zello - Zello's push-to-talk app redefines the walkie talkie. It's a great push-to-talk over cellular (PoC) alternative for businesses and organizations. Learn more about the best walkie talkie app in the market.
Voxer - Turn your phone into a Walkie Talkie. Don't waste time on phone calls and voicemails.
Hibox - Hibox is a mobile app that primarily functions as a platform for collaboration between team members. The software helps maintain communication while a team works on a project, and it provides privacy while supporting the pipeline.
Sameroom - Chat interoperability-as-a-service
Walkie-Talkie.io - This completely free walkie-talkie app online allows you to communicate quickly and easily with your friends. Go to the same radio frequency, push to talk and that's it! There is also a mobile iOS version and always 100% free !