Autoanswer and Server side auto answer.

Zoiper 3 Biz supports both Autoanswer and Server side auto answer.

Autoanswer is a BIZ feature, It is not available for the free version of Zoiper.

Enabling  Auto answer in Zoiper 3:

Open the Settings menu and select Automation

A new window will open. Configure it by your own preference.

Instant auto answer will answer all calls immediately.

Auto answer after X seconds will wait before answering the calls.

Enabling Server side auto answer in Zoiper 3:

Open the Settings menu and select Preferences;
Click on the Automation icon and select Automation.

Enable "Accept server-side auto answer"