Telegrama

The Telegrama app is designed for operating a cell phone on Shabbat for the use of essential needs only, such as medical, security etc. With this app you can receive or make calls (and messages) using the halachic Gramma principle.
This smartphone app requires an Android operating system version 4 and above.
This app requires a specific handset speakerphone marketed by the Zomet Institute, equipped with an internal electronic system based on the Halachic principle of Gramma (see below Halachic Background).
The app is free and can be downloaded from the Google Play store
This app gives you access to your contacts on the smartphone, based on the Halachic principle of frequency shift capacitance Gramma (see below Halachic Background).
B. Speakerphone;
This speakerphone has two buttons: A general Gramma button and a button for calling someone from your contacts.
The buttons respond within 4 seconds, using Gramma (indirect activation).