When activating windows, which type of volume activation is used to activate multiple windows systems, but must be individually activated with microsoft using an internet connection or by telephone?

The answer is MAK. It is also known as Multiple Activation Key. MAK activates systems on a one-time basis, using Microsoft's hosted activation services. Each MAK key is a good for a specific number of device activation. MAK keys are not the default model for Volume Activation clients, so users will have to request MAK keys from the Volume Licensing website if they want to use this model.