Devices, softwares methods hand off a live call from an original leg of a
first modality (such as Circuit Switched Voice) to an alternate leg of
another modality (such as Voice over Internet Protocol). An original leg
of a call is established using the first modality. Then the alternate leg
of the call is established using the second modality, while the first leg
is still established. Then the call is handed off from the original leg
to the alternate leg, while the connection is active.