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.