Download app from Google Play store here: https://play.google.com/store/apps/details?id=org.linphone
After installation start the app.
You might be prompted by Android OS to allow access to your address book and microphone. Please allow.
You now can see an unconfigured softphone running with dial pad.
The indicator shows that it is not connected to a VOIP provider.
Tap menu button and select "Assistant" option.
Select "USE SIP ACCOUNT"
Enter your "SIP account ID" in the Username field.
Enter Password for your "SIP account ID" in the Password field.
Enter your sip server address for your "SIP account ID" in the Domain field.
Select UDP for transport type.
These credentials above can be obtained at Equipment tab via KOMPaaS Portal.
Below an example of successful account setup, although you need to check few things there.
Click on the account and check the following settings:
Tap on account:
Allow push notification - ON
Expire - 120
Navigate back ant tap to "Audio"
Enable only these two audio codecs below, as only they are the supported ones.
Navigate back and select "Advanced" settings
Background mode - ON
Start at boot time - ON
Scroll down to the bottom lines to Android section.
Battery optimization menu → Depends on android you are using: select Don't optimize
Power management settings menu → Depends on android you are using: for Autostart select: ON
The configuration is done.