Microsoft applies to patent "answering machine detection using speech recognition"

The US system of patents is patently (pun intended) very different from the UK
one. It seems to me that Microsoft's latest patent application is decidely
obvious, and is not-very-far-removed from techniques already in use for
outbound dialling systems; basically it amounts to a "liveness" test of what's
on the other end of phone... which is all very well until I implement a
speech-enabled voicemail application that answers back :-) The abstract
follows:

An answering machine detection module is used to determine whether a call
recipient is an actual person or an answering machine. The answering machine
detection module includes a speech recognizer and a call analysis module. The
speech recognizer receives an audible response of the call recipient to a call.
The speech recognizer processes the audible response and provides an output
indicative of recognized speech. The call analysis module processes the output
of the speech recognizer to generate an output indicative of whether the call
recipient is a person or an answering machine.[click heading for more]