I received another one of these calls yesterday.  This time I recorded the answering machine message.  It said the following:

"Hello.  This is a service verification.  We will call you back later.  Thank you."

Today I once again received a call.  This time I choose to answer for once to see what would happen.  It ended up being a sort of survey about Yellow Book.  They asked me a few questions regarding whether I have a Yellow Book directory currently, whether I have used it online, and if I have ever bought anything or a service as a result of it.

After that they thanked me and said they would send me a free two week subscription to my county newspaper, The Patriot News.  

The caller was courteous and I wasn't at all annoyed.  

Now, I cannot say whether all phone calls from this number will be similar or not.  Time will tell in seeing if I receive any future calls from them.