New idea: outsourced virtual office and sales management and technical support for start-up technology companies expanding to new countries who can't yet afford to open their own office. Should we do phone interviews with prospective customers or just email a survey?
In terms of validation, there is no right or wrong.. phone or email is just a tool. i would prefer face to face interaction during targeted networking session.
preparation before you proceed with validation is important. start with potential client that you're comfortable with.
The easy part to ask questions.
The real work is
1. to define the right question to ask
2. establish a connection with potential client before you ask question.
I've seen many entrepreneur ask questions for validation.. end up not getting the real answer, because their respondents somehow not ready to answer it.
I hope this tip would be useful for you. Good luck.