Is "ringing somebody up" exclusive to telephone use in British English?

The Oxford English Dictionary clearly states:

ring: [trans., Brit.] call by telephone

The Cambridge Advanced Learner’s Dictionary also says “to make a telephone call to someone”.

Though it's always hard to prove a negative, I've never seen it used for something other than a telephone call, and looking through some recent Google Books excerpts doesn't bring any other use either.

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It may be localized, but 'ringing someone up' is used in the American mid-atlantic area to refer to the process of tallying someone's purchases at a store, eg:

I can ring someone up in this line. (said by a cashier who is unoccupied)

or

She's ringing someone up right now, but will be with you in a minute. (when you ask to see the manager, and she's occupied.)

It just means to make a telephone call. It is never used in relation to till operations, in the form "ring up". You might ring up some items, though.