Testing ur product or Application with other competitors 
Products or interface.

Hi Maverik ,
Interoperability testing means testing the Application 
under different Hardware and software Configuration and 
checking weather it is working fine or not.It is basically 
a networking testing concept.

Interoperability Testing  can validate that two products
work together and yet neither may be in compliance with the
specification. This often happens when sets of two products
are tested in a pair-wise manner but the sets are not tested
with other standards compliant products. This situation
occurs for various reasons - foremost being the lack of
universal test cases and unclear testing procedures. The
principal risk in this sort of testing is that pair-wise
subsets of the product may be interoperable, yet the overall
set of products fails to communicate properly.