How can I enable Caller ID for outbound calls?

First of all, you can specify Caller ID if it was previously verified or if it's a number that you received from Voximplant. There are two ways to verify custom Caller ID: using Control Panel -> Settings -> CallerIDs or using the VerifyCallerID method of HTTP API. Caller ID can be specified within the VoxEngine scenario using the callPSTN function as the second parameter.