This means that the user you are trying to call has either:

1: Rejected your call request
2: Put you on refuse for this session (in which case, they will not receive any QMs you send during this session)
3: Put you on permanent refuse (in which case, they will not receive any QMs you send unless they remove you from their Refuse / Ignore List)
4: Has not responded to your call request within a set period of time (normally 20 seconds) and the call has automatically been rejected

This means that the person is already in a call / connect and cannot receive a call / connect request from you.

The user you are trying to call or connect to is either recording an Audio QM or their audio is not available at the current time..

The user you are trying to call has issues with their webcam. Most likely their camera has crashed but they have not set their iCu2 to "Do Not Send Video" in TOols - options - Ports. Alternatively they can try restarting their computer so that their camera works again.

This indicates that the person you are trying to call / connect to is currently in one of the User Created Public rooms (listed at the bottom of the directories). To be able to call that person for a private connect, the person must enter one of the main directories

The person you are trying to call / connect to has a networking device or firewall that is not configured correctly for iCu2. Simply put, their networking device / firewall is blocking you from establishing a direct connection to their computer for live video chat.

The person you are trying to call / connect to has a networking device or firewall that is not configured correctly for iCu2. Simply put, their networking device / firewall is blocking you from establishing a direct connection to their computer for live video chat.

The person you are trying to call / connect to has a networking device or firewall that is not configured correctly for iCu2. Simply put, their networking device / firewall is blocking you from establishing a direct connection to their computer for live video chat.

This means that the person you are trying to call has setup their iCu2 to only accept direct connections (SAC means "Server Assisted Calling"). If the call fails, it indicates that the person you are trying to call has got a networking device or firewall on their system that is not configured correctly for direct connections on iCu2. Unfortunately there is nothing you can do about this. It is something that needs to be resolved by the person you are trying to call / connect to.