You use to be able to get battery powered tone generators for phones you just hold up to the receiver, radio shack use to have them for like $7 or so. You hardly ever see them anymore because there's probably only a half dozen places where pulse lines still are in use, but they are available from time to time.

There's one here on e-bay


http://cgi.ebay.com/NEW-Pocket-Telep...QQcmdZViewItem

but it doens't say if it has a memory or not.