Appeal No. 2001-2270
Application 09/235,529
30 dB); and "AT&T central office switches typically reject DTMF
tones less than -38.2 dBm per tone" (spec. at 9, lines 17-18),
which teaches that the attenuation should be greater than
38.2 dB. Thus, if one or ordinary skill in the art wanted to
determine how much attenuation would be required so that the
central office would not detect the DTMF signals, this knowledge
appears to be readily available in the art. We conclude that the
examiner has established a prima facie case of obviousness.
Appellants argue that the Stevens system does not provide
adequate attenuation (Br6).
The examiner does not rely solely on Stevens. However,
Stevens expressly teaches that the attenuation should be enough
so that the central office will not detect the DTMF signals. It
was evidently known in the art that an attenuation of at least
30 dB or 38.2 dB was required to meet this condition. In
addition, Eaton discloses that the DTMF tones should be
attenuated by 30 dB, which suggests that the attenuation in
Stevens also be 30 dB.
Appellants argue that the examiner's rejection states (at
FR6) that Stevens can be a parallel or series device while Eaton
teaches a series device and since both references teach the use
of a series device, it would have been obvious to utilize the
30 dB teachings of Eaton in Stevens (Br7). It is argued that
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