Hi Alex,
Once again nice to have some light shed on this...
Well this question came up today in my IFR Comms exam, I went for "Contact XXXX on 132.010" and not "Contact XXXX on frequency 132.010" It also had two other answers with Channel in them, if I recall correctly it was ( I can't recall to whom it was addressed to but I sure this is not important, let's just say "Tower"):
a. Contact Tower on channel 132.010
b. Contact Tower on channel 132.0089
c. Contact Tower on frequency 132.010
d. Contact Tower on 132.010
The others in my group seemed to go for answer "c". I must admit to hovering between answers "c" & "d", but after reading what you put answer "a" would seem correct too.
Would this be worth contesting?