Huge Holographic Head: Mostly averted, because while a perfectly trivial piece of image manipulation, even the usual suspects have long since figured out that it’s really hard to be taken seriously by people you’ve invited to stare right up your Huge Holographic Nostrils.
“Be advised that the operation of transmitters or other equipment designed to jam, block, corrupt, or otherwise interfere with communicative signaling in the bands allocated to multipurpose mesh networking (see Electromagnetic Spectrum Global and Regional Allocations, latest edition) is a violation of the Free Communications (Trusteeship) Act (1462), as amended. This Act prohibits, enjoins, and binds by law any sophont from willfully interfering with mesh network communications of any type, proprietorship, format, protocol, or purpose carried out over the aforementioned frequency bands.
“Sophonts and/or coadunations in violation of this act shall and must be subject to the penalties provided for under the Act, including but not limited to fines beginning at one sur-doceciad esteyn and scaling geometrically with volume affected, full compensation of costs for all affected parties, and memetic rehabilitation and reconditioning.
“Be further advised that, inasmuch as multipurpose mesh networking protocols are used to fulfil a variety of essential infrastructural and personal safety functions including but not limited to smart grid coordination, health monitoring, emergency response, road-grid and vehicular coordination, et al., the Actions Willfully Prejudicial to Public Safety Act (710) empowers the Imperial Emergency Management Authority to order the immediate destruction of the aforementioned equipment by whatever means it shall deem necessary in order to maintain these functions. Since the act of operating such equipment is classified as a violation of property rights in spectrum with intent, no compensation is due or will be paid for collateral damage to other properties of the equipment operator.”
– a rather important warning label
Talking Lightbulb: While it’s not always one of these, most people wearing all-concealing environment suits, etc., or using off-the-rack bodies with non-unique synthesized voices generally do have some sort of “I’m speaking now” indicator on the outside, if only so that people can tell who’s talking when they’re in a group.
Subspace Ansible: The tangle channel, which involves manufactured entangled (not in the standard quantum sense, note, because we know that doesn’t work; these are ontotechnological devices using the “privileged channels” a long way behind those) particle-pairs. This makes them quite expensive (since they are a consumable resource, one particle per bit transmitted, and have to be shipped there the long way once you separate the ends; if you don’t have one or a stargate, your best option is a lighthugging communications torpedo) at least relative to using light-speed EM communications and relaying them through the stargates, the way most of the non-priority extranet works, but they’re invaluable for priority communications and beyond the reach of the stargate plexus. (They are, for example, the only means of ready communication available to lighthuggers.) And yes, they do work for mindcasting.
(And, yes, they can also let you play interesting games with causality. Just as expected.)
That said, extensive use of caching, prefetching, and AI traffic prognostication makes the extranet delays mostly invisible in practice, as does the ability to engage in pseudo-real-time communication by sending a partial copy of you along with, or as, your message to be able to have a real discussion with the recipient, then reabsorb it when it returns.