I assume you are looking for good answers to the "how much do you charge? " question.
Assuming that this is a variably-priced service question, the starting point of my reply is along the lines of: "it depends upon the nature of the work - what exactly are you trying to do? " Then keep asking questions.
You obviously need more information to prepare a quote (as you presumably recognize). The danger is being tied into a low or unrealistic rate because you incorrectly assumed you knew what the client wanted, what travel etc. was involved, and how much the client was prepared to pay.
If you really can't get away with not quoting a rate, quote a wide range "which depends upon the nature of the work, the travel involved, the technical risk, the length of the contract, and other factors which have to be costed into the equation. "
The only book which rings a bell is: Secrets of Successful Telephone Selling: How to Generate More Leads, Sales, Repeat Business, and Referrals by Phone.
You can check out the reviews on Amazon: http://www.amazon.com/Secrets-Successful-Telephone-Selling-Referrals/dp/0805040986 This is the only book I know which specifically deals with selling on the phone.
Best of luck.
Go with the Who, what, when, why, where line of questions to get as much info as possible from the caller. Create scripts to conistently ask and get the same amount of info. Use your time to indicate how you provide value outside of price.