Comm Link: In the modern era, the ubiquitous neural lace, which is actually built into your brain, or at least, wrapped around your brain so you can talk with your thoughts. Earlier than that, the wearable virtual interface, which was worn as fancy glasses and a few other discreet devices, and subvocalization was the order of the day. Earlier than that, the ubiquitous (and often still carried as a display/collaboration device) terminal, which was basically a fancy smartphone/tablet, only with more computing power and based on mesh networking sending digitally encoded audio in encrypted network packets rather than our cellular system (see Can You Hear Me Now?) – its descendants still use the same back end.
By themselves, they don’t help you accessing alternative communications or if you’re outside of the range of their parent network, but you can add supplemental devices to your personal-area network to interface with alternative systems, or reach the network from out of range via relay, satellite, or even tangle.