I am confused about ISR G3 CUBE high availability (box-to-box redundancy). I need to plan CUBE (ISR 4431) redundancy with calls preservation. Do these gateway serries support that function? I just saw some information about ISR G2 and ASR platforms, and i can't undrestand correctly do i need to redundancy group configuration or it must be a HSRP?
If it possible, please provide any references and explain which licenses i have to use at CUBE for the proper call preservation functionality.