What is the benefit of using a payphone in this case?
It might just be to create a sense of allure. Taken from the movies. Like you are a spy now, dog.
It might be to keep other people around you from accidentally finding out you are a spy.
I personally think it's a little bit this.
I know someone who applied to be an intelligence analyst agent in the UK. First stage was a multiple choice exam in a London hotel, where they had to turn up and say they were there for "KRNP Recruiting" or something. Now the hotel staff must have known something was going on, and it wouldn't be to hard to find this out ... but I reckon it filtered out both ppl who didn't take it seriously and also people who enjoyed that kind of subterfuge a little to much :-)
(honestly can't remember exact letters now)
Phase 1 - Post ASIS Foriegn Intel page to HN, creating noise
Phase 2 - Apply for ASIS Foreign Intel
Phase 3 - Profit
Too bad it only work about once a year.
"If you wish to contact ASIS on another matter, please write to: Locked Bag 41, Kingston ACT 2604. Canberra, Australia"
That's a first for me!
"If you wish to include data in your application which is classified higher than 'IN-CONFIDENCE', please indicate in the 'Additional Comments' section of the application form that you have further classified information which you feel is relevant to the success of your application. Should ASIS determine it necessary to discuss this classified information with you, this will be done via secure means at a later stage."
This is what public payphone is for, in both directions.
It all feels very James Bond..