1. Find and download Linphone from AppStore.
2. After successful installation, launch the Linphone.
3. Click "USE SIP ACCOUNT".
4. Enter the following details:
USERNAME: Your sip-number (for example 111111) from your personal account
PASSWORD: Your sip-number password from your personal account
DOMAIN: sip.zadarma.com
USERNAME: Your PBX extension number (for example 1234-100) from your personal account
PASSWORD: Your PBX extension number password from your personal account
DOMAIN: pbx.zadarma.com
5. Click "LOGIN". If all settings were entered correctly, connection status will appear as "Registered".