It is a good idea to obtain a separate telephone line into your home or to have a separate cell phone to receive adoption related calls only. Make sure you have a good voice mail message. This way, if the phone rings, you know that it may be a birth mother searching for you and you will be ready to take the call.
You don't want to miss the call because the birth mother is not likely to call again. It is for this reason that you should know ahead of time what you would like to say when the phone rings.
An alternative, is to list the name and telephone number of your attorney, but I do not recommend this. You are the ones the birth mother wants to know about, and lawyers are not likely to be avaialble when the call comes.