Both "communicate with" and "communicate to" are correct in usage depending on surrounding context and the desired meaning you wish to convey.
The verb "communicate" has both transitive and intransitive functions so it could be used with direct or indirect objects, but your confusion is sematic in orgin: some meanings of communicate require the preposition "with" while other definitions require the prepostion "to".
communicate. (n.d.). Dictionary.com Unabridged (v 1.0.1). Retrieved September 01, 2006, from Dictionary.com website: http://dictionary.reference.com/search? ... te&x=0&y=0
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