April 19, 2026
When my phone didn’t want to connect to 5G, I found out about a hidden mobile networking settings menu on Android. The network settings were incorrect, and changing them allowed a successful 5G connection. In this post I explain how to get to this menu, and add a short overview of mobile networking, so that you can understand the settings.
On an Android phone (at least those running some kind of AOSP), you can open the phone dialer and type *#*#4636#*#* (4636 being the keys spelling ‘info’).
This will open a hidden part of the settings, and if you click on the “Phone Information V2” menu (might be differently named on your device), you’ll see some detailed information about your mobile network connectivity.
You also have some things you can change in this menu; for example, you can change the value next to “Set Preferred Network Type”.
When my phone didn’t want to connect to a 5G network, I found that this was set incorrectly.
Note, these settings may not work with all phone models and carriers.
Since this settings area is full of acronyms, I put together a small overview of mobile networking below. I’m not an expert, or really knowledgeable in this area at all; I was learning as I was writing this, and I purposely leave out a lot of details, because this is only intended as a high level summary.
On a phone, you connect to other devices using a “cellular network” (more commonly now called “mobile network”). It’s called “cellular” because the land is split into “cells”, each served by at least one transceiver (also called base station, cell tower, etc.). Your phone connects to the cell tower with the strongest signal.
First, some basics on sending data via radio waves. A carrier wave oscillates at a known frequency, and you can modify (“modulate”) the wave to encode information. The properties you can modify are frequency (how fast it oscillates), amplitude (how powerful the wave is), and phase (where in its cycle the wave is at a given moment). One problem is that if you have multiple people modifying the same properties of a wave, how do you distinguish between them? The next problem is is, how can we send more data faster? For that, either you increase the channel bandwidth, increase modulation complexity, or use multiple sending/receiving points.
1G first introduced the cellular network, but it was only analog. It used FDMA: frequency division multiple access. Each user got its own part of the frequency spectrum, and occupied that part for the whole duration of a call.
2G was the first digital approach, with common standards being GSM and cdmaOne. For a voice call, the voice was sampled, compressed, and sent as digital bits. 2G also first introduced the SIM card, or UICC: a chip that contains some identifiers and keys, and could also store a phone book and other data.
In GSM, TDMA (time division multiple access) was newly used: each user got a short window of time when it could transmit on a channel, and the base station synchronized this. Each cell used a different set of frequencies compared to its neighbors, so that it wouldn’t interfere. As a signalling channel side effect, we got SMS for text messages: the network used a dedicated channel for small control messages (e.g. alert about incoming calls, instructions to switch channels), and when that channel wasn’t being used, we could send an SMS (which was limited to 160 characters so that it could fit within the signalling message). Later, GPRS added packet switching, so we could send data, and EDGE made improvements in the modulation scheme, increasing the available data rate.
A competing standard was cdmaOne This used CDMA (code division multiple access): a user’s data was spread across the whole frequency spectrum, using a unique code, which ensured it didn’t interfere with codes of other users. cdmaOne had SMS too, but it had to be retrofitted, with translation infrastructure needed between cdmaOne and GSM. It also had a standard for data transfer: 1xRTT, which evolved into EV-DO.
In 3G, basically all standards used CDMA. To increase the speed, they tried to widen the frequency band, and improve modulation. The first standard was UMTS, which used a wider frequency band (WCDMA), allowing higher data rates. It was then improved upon by HSPA and HSPA+, which used adaptive modulation: the base station chose more efficient modulation for good signal conditions, and more robust when the conditions were bad. 3G was the last to use both circuit and packet switching in hybrid: voice calls used circuit switching infrastructure (a path between two callers was reserved for the full duration of the call), and data used packet switching.
With 4G, mobile networking moved fully away from circuit switching to IP: voice calls are “VoIP” (VoLTE), just another stream of data. The common standards here are LTE and LTE-A. Here, they didn’t stay with CDMA, because it would not be as good for high data rates (inter-cell interference, harder rejection of interference at high rates since you have less spreading, and problems with multipath). Instead, it uses OFDMA for downlink and SC-FDMA for uplink.
Finally, at the time of writing, the newest technology is 5G, with the NR standard. It still uses OFDMA, but with much wider channels. 5G base stations (“gNB”) have many more antennas (this is called “MIMO”), so instead of transmitting in all directions like in earlier generations, it can point a focused radio beam to specific phones and track them (“beamforming”).