Yes, there is a reason the IRS has requested a response and it will not take care of itself without you being involved.
The IRS expects you to be fully knowledgeable in the tax law and all released publications and updates. They have many different departments and representatives each specialized in that area so you will need to call the right person.
This depends on whom you call. Sometimes you may experience several dropped calls before you even have the chance to speak with a representative.