Quote:
Originally Posted by Herald1360
Something to do with the three different charging bands of the day? ISTR "local", "a" and "b" trunk rates.
Whether this had anything to do with how far you could talk on an unamplified circuit, I don't know!
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And 'c' and later 'b1' rates at various time during STD calling. Calls being charges between 'charge groups'
Pre-STD the letters didn't exist. Calls were charged by distance between exchanges within radius bands - see attached map giving the rates from London.
I don't think it had anything to do with 'amplified/non-amplified'