Jeff,
Honestly, I get very little information over the phone. I would much rather speak with this person face-to-face. Here's why:
The majority of investors in my area will do their best to collect most of the information before hanging up the phone. When I am selling a house I have investors calling me all day long. It seems like they often ask the same information, off of the same 'guru' question sheet. There are usually a couple questions about the house and then everything turns to my situation. "Are you motivated?", "Why do you need the money for?", "Would you prefer if someone were able to offer you a quick cash offer?". It is really pretty funny.
Then the questions turn to MY mortgage. "How much of a mortgage do you have on it?". Do you think this is an appropriate question to ask someone over the phone? This guy has never met me and he is asking how much I owe on my house. Then the question about taking over payments comes into play. "Taking over payments, I thought you just said you only pay cash?" And what distressed homeowner really knows if their mortgage is assumable, "Yeah, I haven't paid my mortgage in 3 months, but I remember that clause 45 said it is assumable."
Then, about half of the time, the investor will submit an offer right there over the phone. He will list all of the negatives on the property and throw out a very low figure hoping I will show some sign of interest. This guy hasn't even seen the INSIDE of the house, yet he is telling me how much he thinks it's worth. It just screams tasteless.
While I understand that most investors are doing this to a lot of homeowners and do not have the time to visit with each one of them. I strongly disagree with handling your business with these people solely over the phone. Take the time to visit with these people face to face. Sure it will take a drive to their house, but you may be able to secure a really good deal because of that one drive.
When I receive a call from a mailing, I get the person's name and address and ask them what would be a good time to meet. If the answer isn't "Anytime!", or "Right now", then I get some info over the phone. With a name and address you can take 5 minutes online and find out what their round-about mortgage amount it.
Building a relationship with these people will make them feel more comfortable in what they are doing....and it will make you much more money.