 As the most important topic for some, managing mobility has always been a concern since mobile communications came into existence. There are so many interesting aspects to mobility that mobility management is complex yet interesting. We will touch upon some types of mobility which are consequent to the heterogeneous environment of the next generation network. We have wired networks, wireless networks and we have different interfaces, connectivity, paradigms, latency, packet drop ratio, link strength, etc. So consequently some issues pop up which need to be handled so it means we are now going to look at the mobility in terms of specifics. Let's start with terminal mobility. The handset or the user equipment which moves from one network to the other or from one location to the other may be in the same network, may be two different networks at the same location could be any combination of both. The terminal mobility actually requires the terminal to access the telecom services preferably not disrupted in an undisrupted manner from different access networks which are available to the user equipment as it moves and across different locations. When we say locations it could mean literally the geographical location or the IP addressing of that particular network. This is the expectation or the design feature which is to be provided in the user equipment or the terminal. There is equal responsibility on part of the network as well to have the capability to identify a mobile or a roaming user, locate it that is to determine its corresponding location and provide its services through the most appropriate interface. The next one is network mobility. It means that there is a possibility when a group of nodes each having its own unique identifier tend to move in a group from one place to the other that is either changing the network or changing the location, changing both could be anything. So in that case if these nodes move together in the form of a group then the entire group has to be provided connectivity that means when it changes its location or network from one point to the other network mobility implies that such group has to be provided connectivity as a group. It means all the group members are entitled to connectivity. It's quite challenging actually. Then we have personal mobility. This is as simple as you being a user moving from one mobile to the other to the other changing the brands, changing the mobile phones every year or every few months. It means that when the user changes the mobile terminal while it is connecting to a network at one place and it is moving or the user chooses to move after changing the device and then moving it could be any combination of these. The user needs to have continuity of service. Since the user is now being given the leverage or the flexibility to change its device as it will, so correspondingly the user has to be given a unique identifier so that it can be identified from a different mobile set or from a different terminal. It means when a user is moving from one network to the other while it's changing its terminal, it still has to be recognized as a particular user because the user has signed a contract as service level agreement with the network. So the onus on the network is the network actually has to deal with such tricky users. So the identifier based database record has to be there in the network as well. Then we have service mobility. Service mobility has different definitions. In terms of simplified definition, it can be said that a service has to be provided in continuity regardless of the user's changing location or user's choice of using a terminal at one point and another terminal at another. This is what service mobility can be understood in the simplest possible manner. However, the definition of service mobility can vary. For instance, another definition of service mobility can be that the service can be mobile from one network to the other. It means it would be now binding on the networks to provide that service regardless of the origin of the service provider. It means the application servers now have to be synchronized so that they provide the same service or set of services for a user or a terminal moving at will.