A Galaxy S23 with no service, slow mobile data or no 5G icon is most often a carrier, SIM or network-mode matter before it is a modem fault. The US S23 uses a Snapdragon X70 modem with 5G sub-6 and mmWave support, one nano-SIM and one eSIM. Check Mobile networks, reseat the SIM, restart, and ask the carrier whether the line or the eSIM profile was changed. Reset network settings clears a corrupted mobile profile.
Differential
Likely causes of “Samsung Galaxy S23 has no cellular service or data”, and how to tell them apart
- 1
The wrong network mode
What separates it No 5G, or constant switching between 5G and LTE
How to confirm Settings, Connections, Mobile networks, Network mode: 5G/LTE/3G/2G (auto connect)
- 2
A SIM seated badly
What separates it SIM not detected or No service after a drop
How to confirm Power off, remove the SIM tray and reseat the nano-SIM
- 3
A carrier outage or account issue
What separates it No service for others nearby
How to confirm Check the carrier's outage page or app
- 4
An eSIM profile fault
What separates it The carrier name is missing
How to confirm Ask the carrier to re-provision the eSIM
- 5
A corrupt network profile
What separates it Data fails despite good bars
How to confirm Settings, General management, Reset, Reset network settings
- 6
Roaming or data roaming off
What separates it No data when traveling or on a partner network
How to confirm Settings, Connections, Mobile networks, Data roaming: turn it on if your plan allows it
Before you touch a setting
Record this first — changing settings destroys the evidence
- Carrier and whether the line is a SIM or eSIM
- Bars, network type and mode
- Whether other phones on the same carrier work
- One UI version and patch date
Try in this order
0 of 6 completedToggle Airplane mode
ReversibleOn for ten seconds, then off, so the phone re-registers.
Check network mode
ReversibleSettings, Connections, Mobile networks, Network mode: pick the auto option that includes 5G.
Reseat the SIM
ReversibleSwitch off, remove the tray with the ejector pin, check the SIM is clean and flat, and reinsert.
Update the phone
ReversibleSettings, Software update, Download and install; carrier updates arrive with it.
Reset network settings
Reset / data riskSettings, General management, Reset, Reset network settings.
Call the carrier
ReversibleAsk them to refresh the line, check the SIM or eSIM provisioning and confirm no suspension.
Model-specific
What is true of this model and not of its siblings
- The S23's modem
- The US S23 uses a Snapdragon X70 modem with 5G sub-6 and mmWave, one nano-SIM slot and an eSIM. International models differ.
- What a carrier can see
- Your carrier can show whether the SIM or eSIM is active, which towers the phone last used and whether the account is suspended.
Stop boundary
When this stops being a self-service repair
- !If a different SIM works in the S23 but yours does not, the carrier owns it
- !If no SIM works, book a Samsung hardware check
- !Persistent No service with a good SIM needs the modem checked
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Does the S23 support mmWave 5G?+
The US models list 5G with sub-6 and mmWave.
Why do I not get 5G on my S23?+
Coverage or network mode; the auto mode includes 5G where it exists.
Does the S23 support eSIM?+
Yes, alongside one nano-SIM.
Does Reset network settings remove the SIM?+
No; it clears network configuration only.
Why does my S23 say No service in one room?+
Signal in that room is weak; Wi-Fi Calling keeps calls going and moving to a window shows whether it is the building.
Can I use two numbers on an S23?+
Yes: the nano-SIM and the eSIM can both be active, and SIM manager sets which one handles calls, texts and data.