Why in LTE architecture there is need of distinguishing between home network and visitor network while in 2G/3G there isn’t?

As per my understanding the concept of Home network and Visitor network concept was existing in 2G/3G, Basically service providers use this concept to identify that Mobile User is in roaming or not. If the user is in roaming area i.e. visitor network the services and charging will vary since the user is using network resources in visitor location. e.g Consider user ‘X’ brought a 4G mobile from T-Mobile in NYC and this becomes Home network for him. After some time user ‘X’ moves to dallas,Texas then it becomes a visitor network.

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