Tolkien on unwanted calls

From Tolkien's collected letters:

From a letter to Joy Hill, Allen & Unwin

10 May 1966

[Tolkien's telephone number was still in the Oxford directory, and he was sometimes bothered by calls from fans.]

Thank you very much for your suggestions about my telephone number, which I will consider. Removing the number from the directory seems better than the method adopted by Major W.H. Lewis in protecting his brother [C.S. Lewis], which was to lift the receiver and say 'Oxford Sewage Disposal Unit' and go on repeating it until they went away.