From VoiceMailTel Wiki
1. Download and install the soft phone
Click Download ZoiPer. After downloading the software, install it and configure it according to the steps below: Click on the downloaded file to install it.
Click "Run" in the notification window.
Click "Next" on all setup windows until the installation is completed.
2. Setup your Zoiper softphone
Click "Continue as free user" on the first setup screen.
Enter your SIP user name in the following format: "firstname.lastname@example.org". Enter your SIP terminal password.
Click "Next" on the next screen without changing any information.
Make sure the "Optional" box is checked, confirm your SIP user name on the next screen and click "Next".
Look for the SIP UDP option to turn green and click "Next".
Look for a green check mark sign in the upper left corner of your soft phone, which will confirm your setup was completed successfully.