I am speaking from a feature (cell)phone’s point of view. I don’t know if my MNO/MVNO service signal is just dropping/dropped out at times (had to adjust the settings to listen for 3G and mobile data connection [I don’t have data plans, but the operators may help improve signal transmission/reception with this customer option {none of that 4G/LTE mess, that generation standard tends to conflict its wireless cellphone call/text and data services; parts of the world may still use 2G, I think that the Librem 5 may find growth in such markets}]).
Airplane flights are the usual culprits behind dropping/dropped cellphone signals. I think that its mass/radio is the key factor of interference. Not only that, but according to Why is Cellphone Signal So Weak When You Load Onto A Plane? - Your Mileage May Vary, cell towers cannot be near airports due to radio/plane interference. This misfortune is just a fact of life.
I would prefer an alternative telecommunication approach, but that would be in the future.
For now, I was thinking to recalibrate 3.5mm FM radio antenna hardware/firmware to transmit and receive cellphone calls/text. In addition, it must maintain cellular network connectivity, on the cellphone’s end. Just think of it like its own portable radio tower. It’s a funny thing that cellular signals can drop out, but the radio signals can keep on going, despite its variable quality. Even better, what if radio signals can be improved to act as a sufficient cell tower? That way, there be at least, a wider signal coverage. Of course, cellphones need to be adjusted to act like radios. I don’t really mind the extended antenna rod, even automobiles still have their own radio antennas (the older ones are still better). I admit that I doubt that radio antennas could keep signal uptime near airplane flights, but at the very least, I hope that they will maintain connection despite airborne interference. I don’t think I will have the chance to use such technology in reality, but one can dream of innovations.
FM broadcast and cellular use completely different frequency bands and in general can not use the same antenna.
There have been devices that used plugged in headphones to enhance FM broadcast reception, but I doubt the same could be done for cellular reception. However, it is possible to provide a connector for an external purpose designed cellular antenna, but I do not know whether any modern phone has had one.
I don’t think that this type of technology would be supported despite the convenience and compatibility. I do like that university research. Publication was two years ago.
For now, the alternative method is to attempt VOIP or call on wifi. I skimmed the Session Initiation Protocol wiki, and it says something about video calls. I might explore softphones and USB phones too. Plenty of detail to sort through, but I hope I get somewhere with this.
Mobile phones on aircraft - Wikipedia
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And since the aircraft is moving at a high speed, cell phones will try to reconnect to every base station it passes over, as cellular devices are meant to connect to a base station that has the strongest signal. This can cause interference with cellular services on the ground.
According to the wiki, mid-air radio/cellular connection interferes with devices on ground level. For sure, 4G will eventually get disrupted by a passing airplane. Not sure if the fault points to either cell phones, smartphones, or radio. I say that each airplane should have its own station for radios/phones onboard. Planes may need some signal blocker in its bottom surface. As for the radio/cellular tower/station on ground, maybe its reception should be for lower levels.
5G might be the better convenient answer to the noise. As a phone, Librem 5 and Liberty Phone do not have 5G modem at the moment (that fact is not the reason for my purchase though).
Ironically, AweSIM, SIMple and SIMple Plus cellular plans include 4G LTE/ 5G LTE data and unlimited talk time and texts within the USA. International calls and SMS are charged separately. Wouldn’t the limits of the current cellular modem restrict any 5G type calls/texts/data?
I have found two Andriod-based Linux smartphones that claim to have 5G modems. Their firmware may or may not support mobile Linux OS flash image/sim installation. Each company differs on tech support for mobile Linux OS compatibility. Another problem is that one doesn’t know how well they work for American continents. I won’t go over the details regarding pre-order and shipping. Would at least test out their OS, but no access. Have to say that while they do have contact mediums/forms, email address could been the easier solution (minus the need to forward aliases, etc). I was thinking that why isn’t there a 5G feature phone too, but I guess that’s a mystery for another day.