PrivateGSM Enterprise
Quick Start Guide for Android

This guide provides you easy step-by-step instructions to help you get started with PrivateGSM Enterprise.

Making a secure call with PrivateGSM

Calling with PrivateGSM is very easy. Select the “Contacts” tab. After your address appears and select a contact to initiate a secure call.


figure 1. application main view
figure 2. your address book is shared with PrivateGSM


The Presence avoid users to call contacts who are not reachable, eg: because they do not have PrivateGSM activated and/or connected. The main value of this feature is to improve user experience suggesting the possible outcome of a call.

Contacts lists

Starting with the present version, there are three lists:
  • BASE: it lists all the contacts which are in the mobile address book, ordering them in the very same way.
  • KNOWN: it shows only known contacts (registered or not) according to PrivateServer's knowledge. This means it is a list of the contacts that are recognised by the server and thus can have a status.
  • FAVOURITES: it reads the contacts marked by you as "PrivateGSM favorites". It's a selection of contacts you choose to have apart, in order to make speed calls.
Each list may show a Contact status beside each contact. The contact status legenda is shown below:

Contact status

OnlineThe contact is reachable. You can make a secure call to the user. 
OfflineThe contact is not reachable, because is not under network coverage or is offline. You can try to make a secure call but the call will likely fail 

The contact is not reachable using a full secure call, but you can call him using the unsecure Sip Trunk configured on your server. 

Enterprise version only!


ErrorThere is a comunication error between your phone and the server. The contact status is unknown, anyway you can try to make a secure call 

To make a secure call, you and the called party must have PrivateGSM software running on the mobile device, be connected to the Internet and to the same SIP server.

You can make a secure call to any arbitrary number (presuming that the call peer has PrivateGSM connected) by selecting the “DialPad” tab and entering the number.

figure 3. PrivateGSM dial pad

Receiving a secure call with PrivateGSM

Once PrivateGSM is installed and all the settings are correctly configured on your device, you are able to receive a secure call. PrivateGSM displays a screen when an incoming secure call is arrives to your phone. Press the Accept button to allow the connection. After the system have exchanged and verified the security keys the you can start the conversation.

To receive a secure call PrivateGSM has to be running and be connected to the Internet.

figure 4. you are receiving a secure call

Call status

To establish a call PrivateGSM completes three phases shown by three icons:

Call status icons

Red light

Starting the connection

Connection not yet established. This step may take several seconds

Yellow light

ZRTP-edition ONLY

Key exchange

Connection established but encryption keys are being exchanged.

Green light

Secure call established

Connection established and secure. You can now speak securely

Checking your security

A PrivateGSM call is always encrypted. The call is automatically secured during the call setup. As soon as the call is established you can immediately start to talk securely with your call peer.

The security of the call is based on a digital certificate verification on the SIP/TLS server. If a certificate error appears check whether the date of your phone is correct. If the date is correct it is possible that the certificate is wrong, misconfigured or expired or that your phone is undergoing a security attack. In these cases always contact your system administrator.

figure 5.
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