The topic pretty much covers my question. My protagonist has to keep in touch with his employer over the course of the story, and something like a cell phone seems the most sensible way to do it. I can't recall if such devices are ever mentioned in Siglerverse canon, and even if they are, I'm not sure where to start looking.
I guess I could just call it something generic like a "personal communicator" and give it some nifty futuristic features like a 3-D holographic display or something. But if there's already something that fills that niche, I'd prefer not to introduce new technology to the Siglerverse.