1. Install SFLphone.
2. Launch the SFLphone and click "Edit".
3. Click "Add" to add an account.
4. Enter the following and click "Apply".
Nickname: Your sip number (for example 111111) from your personal account
Server name or IP address: sip.zadarma.com
Username: Your sip number (for example 111111) from your personal account
Password: your sip number password from your personal account
Nickname: Your PBX extension number (for example 1234-100) from your personal account
Server name or IP address: pbx.zadarma.com
Username: Your PBX extension number (for example 1234-100) from yours personal account
Password: Your PBX extension number password from your personal account
5. Go to "Audio", select "DTMF mode = SIP" and click "Apply".
6. The account is now registered and you can make calls.