Each main base station in the network is served by exactly one VLR (one BTS may be served by many MSCs in case of MSC in pool), hence a subscriber cannot be present in more than one VLR at a time.
网络中的每个主要基站都严格地仅由一个VLR来提供服务（在MSC池的情况下，一个BTS可能由多个MSC提供服务），因此一个签约用户不会同时出现在超过1个VLR上。