En.Lil and his men had implants for telepathic communication. The technology is nearly at hand. In Resurrection and Redemptions (books 3 and 4 of The Alterran Legacy Series), the implants cause En.Lil's abilities to evolve.

Telepathic Communication Has Become a Reality

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How many times we wished to be able to contact someone without words… New company for scientific and military research plans to make the dream come true by giving us a possibility to send text or audio messages by thought. The technology of so-called synthetic telepathy...