In a previous blog article I described that it seems all of the phones at the USPTO are broken for incoming calls. Here is a practice tip.
If the person’s phone number starts “571-272”, then change the “272” to “273”. This yields a telephone number that is probably that person’s private fax number. You can then send a fax and ask the person to call you back.
You can also often guess their email address, for most examiners that don’t have really long names or common names, it is usually First.Last(at)USPTO.gov