Appeal No. 2001-2270
Application 09/235,529
this reasoning would yield a series device, which is contrary to
the parallel limitations of the claims (Br8).
While the examiner's reasoning could be better stated, we
interpret the examiner's rejection to mean that it would have
been obvious to modify Stevens' parallel attenuator to provide an
attenuation of 30 dB in view of Eaton's teaching of an
attenuation between the telephone and the central office of
30 dB, albeit in a series device. The examiner's reference to
both Stevens and Eaton teaching serial devices appears to be only
an attempt to show some commonality between the references rather
than a statement that the device should be serial.
Appellants argue that Stevens requires the use of a waveform
generator circuit to generate an interference signal so that the
central office does not detect DTMF dialing signals, and the
attenuator alone is not sufficient to block dialing signals so
that they are not detected (RBr3-4). It is argued that the
teaching of using an interference signal teaches away from the
present invention (RBr4).
The waveform generator in Stevens is an alternative or
additional means to prevent DTMF signals from being recognized by
the central office and is not required. "A reference may be said
to teach away when a person of ordinary skill, upon reading the
reference, would be discouraged from following the path set out
in the reference, or would be led in a direction divergent from
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