I agree 100% about answering the phone right away to increase your sales opportunity! Perhaps I'm "old school" but I don't believe in giving quotes over the phone, or having pricing schedules listed on a web site or otherwise. This may not apply to all contractors reading this, but I'll offer my $.02 worth anyway.
My experience with giving estimates over the phone, or "off the cuff" pricing on location, is that the closing ratio is 25% or less. I will occasionally give a phone estimate if the caller will not give me an appointment after several requests to do so. I already know by the time I hang up the phone that the chances of hearing from this prospect again are less than 5%. In most cases, before I have given them a "phone estimate", I have engaged them on the phone for 5 - 10 minutes without success in retrieving an address, last name or phone number. It's basically pointless, but I'm the ultimate optimist.
While we are not the largest contractor in our market, we are certainly in the top 3 - 5. We charge top dollar for our service and produce quality results. I point this out not to boast, but to qualify our method of sales. I INSIST on going to every location to view, measure & SELL all call-in requests. My closing ratio for Face-to-Face is 75%. Yes, it irritates me too if I drive 40+ miles for an estimate that doesn't pan out. If at all possible, I will combine this trip with a visit to an existing client, if only to say HI or update them on new info, product, etc. What a lot of contractors don't realize is that if you give pricing over the phone and you're not the cheapest, the only impression you leave with the prospect is that you're too expensive. If you meet with them personally and do your best sales job, and you're still too expensive, you've at least had the opportunity to explain why your service demands higher pricing. Their less likely to state this to someone else because they might come off sounding like a "price shopper". It saves your company's integrity.
Yes, an occasional phone price is necessary, but should not be a regular selling tool. If you receive 40+ calls weekly and can't handle the load, you need to hire a salesperson. I believe this is the exception rather than the rule. If you refuse to give a phone estimate to 1 or 2 prospects a week, but meet personally with the other 6 - 10, you'll be further ahead. Organize, plan, prepare. Selling your personality, performance and reputation will produce more than selling on price. Good Luck!