Repeated and unqualified statements in the prosecution history that the claimed invention treats all elements of a set in a certain manner may preclude enforcement against a system that selectively operates on a subset of those elements. For example, as here, stating that the claimed invention blocks “all” international calls may be taken as a requirement that the accused device treat all international calls the same, in addition to the literal requirement that at least one international call is blocked in the manner claimed.
Background / Facts: The patent being asserted here is directed to blocking potentially fraudulent international access calls, such as those made from public phones using a stolen calling card or via a private branch exchange (“PBX”) system after an unauthorized access to the system. The claims recite blocking international access calls if a certain dialing sequence is identified as matching any of the predetermined digits defined for international calls. In this regard, the claims use limitations such as (i) “selectively enabling” and “transmitting [or transmits] said dialing sequence,” (ii) “predetermined signals [or predetermined digit sequence, or test signal value sequences] which are used to accomplish [or for] international dialing,” and (iii) “means for preventing” and “at least partially preventing operation of.”
Issue(s): Whether these limitations permit selectively blocking of only a subset of international calls having certain predetermined digit sequences rather than requiring the blocking of all international calls from the device.
Holding(s): No. In addition to various consistent descriptions in the specification, the court noted that during prosecution, the patentee “sought to distinguish [the prior art] on multiple occasions by representing to the examiner that his invention would block a call upon a determination that the call is international.” For example, the patentee made the unqualified argument that “[t]hus, my claimed invention restricts dialing of international calls based upon a determination that the dialed call is an international one.” The court even cited the patentee’s apparent attempt to broaden the examiner’s reasons for allowance, asserting that “[the patentee] confirmed and acquiesced to the examiner’s understanding by stating that ‘the fact the Applicant’s claimed invention will block ALL international calls is irrelevant to the decision of patentability of the claimed invention.’” Based on this evidence, the court held that the patentee’s “repeated and unqualified statements that his claimed invention will block ‘all international calls’ extend beyond merely illuminating ‘how the inventor understood the invention,’ … and provide an affirmative definition for the disputed claim terms.”