'Dumfries and district Post Office directory' for 1911-1912
The 'Dumfries and district Post Office directory' for 1911-1912 gives details of charges for phone calls via trunk telephone lines.
It also provides information on the duration of phone calls, saying that the 'ordinary period of conversation is limited to three minutes, but any person may secure the uninterrupted use of a trunk line for six minutes by prepaying a double fee.'
View this page in Dumfries directory, 1911-1912
View the full Dumfries directory, 1911-1912