Direct answer
For the Samsung Galaxy S25 Ultra, carrier outage/account/provisioning, SIM/eSIM, coverage, line selection and device radio should be separated. First, test calls and data in two locations with Wi-Fi off.
What this covers
- Samsung Galaxy S25 Ultra (SM-S938*)
- Samsung Galaxy family; S Pen, foldable display, DeX, USB moisture and One UI features vary by exact model.
- The specific fault this record addresses: has no cellular service or data
What it does not cover
- ×The same symptom on a different Samsung product line, which has its own record and its own cited source
- ×An on-screen error code whose meaning has not been checked against this exact model's manual
- ×Live electrical, gas, sealed-system, internal battery-cell or structural repair — a technician boundary, not a self-service step
Differential
What actually causes this, and how to tell them apart
These are ordered by how often each one is the answer, not by how easy it is to try. The point of the middle column is that two causes producing the same headline symptom rarely produce the same detail — that detail is what tells you which one you have before you change anything.
- 1
Coverage where you are, not the phone
What separates it Service is fine elsewhere and poor at one address, or degraded since a mast change. Indoor coverage in particular varies enormously with construction — foil-backed insulation and low-emissivity glazing both attenuate heavily.
How to confirm Compare with another phone on the same network in the same place. Same network struggling on both is coverage; one phone struggling is not.
- 2
The eSIM profile has been deleted or was never transferred
What separates it No service after a phone swap, a reset, or a repair. An eSIM does not move with the handset the way a plastic SIM does — it has to be transferred or reissued.
How to confirm Check whether the profile is present and active in the phone's cellular settings. A missing profile is an account action with the carrier, not a phone setting.
- 3
The account is suspended, or the line was ported away
What separates it Emergency calls only, on a phone that is otherwise perfect, often on a billing date. The phone reports this identically to a hardware fault.
How to confirm Check the account status with the carrier before doing anything to the phone. This is the cheapest possible check and it is skipped constantly.
- 4
Carrier settings or an APN that is out of date
What separates it Calls work and data does not, or the reverse, after a network change or a phone migration. The APN and carrier profile define how the phone talks to the network.
How to confirm Check for a carrier settings update, and compare the APN against the carrier's published values rather than editing it speculatively.
- 5
The phone is locked to another carrier
What separates it A new SIM produces no service on a phone that worked with its original one. Second-hand and carrier-financed handsets are the usual case.
How to confirm Check the phone's own carrier-lock status in settings. No configuration works around a locked handset.
- 6
Band or network-mode selection excluding the available service
What separates it Service is poor in a place where the carrier claims coverage, or after travelling. A phone pinned to 5G-only or to a manual network selection can exclude what is actually available.
How to confirm Set network selection back to automatic and the preferred network back to its default. Manual selections outlive the reason they were made.
- 7
The wrong line is selected for data
What separates it Calls work on one number and data does not, on a phone with two lines. Data uses one line and it is a separate setting from the default voice line.
How to confirm Check which line is set for cellular data. Two-line phones make this easy to get wrong and hard to notice.
Before you touch a setting
Record this first — changing settings destroys the evidence
Every item below stops existing the moment a reset, re-pair or settings change is made. Written down first, they are what separates the causes above; recovered afterwards, they are guesswork.
- The exact indicator: no service, searching, emergency calls only, or service with no data. These are four different failures with four different causes.
- Whether it fails everywhere or only at particular locations.
- Whether another phone on the same carrier has the same problem in the same place.
- What changed and when: a new SIM, a phone swap, a reset, a repair, a plan change, travel, a billing date.
- Whether calls work while data does not, or vice versa — that split points at carrier settings rather than at the radio.
- The account's status with the carrier, checked before any phone-side work.
- Whether the eSIM profile is present and active in cellular settings.
- Which line is set as the default for cellular data.
Read the exact indicator before doing anything
ReversibleNo service, searching, emergency calls only, and service without data are four different failures. 'Emergency calls only' in particular usually means the phone has found a network and been refused by it — which is an account matter, not a radio one.
Check the account status with the carrier
ReversibleA suspended account, a failed payment or a line ported away all present exactly like a hardware fault, and the phone cannot tell you the difference. This costs one call or one app check and it is skipped constantly.
Compare with another phone on the same network, same place
ReversibleBoth struggling is coverage and nothing on the phone will fix it. One struggling is the phone, the SIM or the account — and the router-equivalent excuse is gone.
Confirm the eSIM profile is present and active
ReversibleAn eSIM does not move with the handset the way a plastic SIM does — a phone swap, a reset or a repair can leave the profile behind. A missing profile is an account action with the carrier, not a setting you can restore.
Separate voice from data
ReversibleCalls working while data fails, or the reverse, points at carrier settings and the APN rather than at signal or hardware. That is a completely different investigation from no service at all.
Return network selection and preferred network to automatic
ReversibleA manual network selection or a mode pinned to 5G-only outlives the reason it was set, and both can exclude service that is genuinely available. Returning them to default is free and reversible.
Check for a carrier settings update
ReversibleCarrier profiles define how the phone talks to the network and they change. Applying an available update is safer and more likely to help than editing the APN by hand, which is easy to get wrong and hard to undo.
Model-specific
What is true of this model and not of its siblings
Generic advice for the product line fails here. Each item below is a property of this specific model family that changes which of the steps above apply to you.
- Model scope
- SM-S938*. Samsung Galaxy family; S Pen, foldable display, DeX, USB moisture and One UI features vary by exact model.
- Display
- 174.2mm (6.9" full rectangle) / 172.2mm (6.8" rounded corners), 3120 x 1440 (Quad HD+), Dynamic AMOLED 2X, up to 120 Hz. Samsung quotes two figures for screen size — the full rectangle and the rounded-corner measurement — which is why this phone is listed at two different sizes in different places and neither is wrong.
- Refresh rate
- Up to 120 Hz adaptive. A high refresh rate is one of the larger discretionary battery costs on this phone: it is genuinely smoother and it genuinely costs runtime, which is why battery complaints on this model are worth checking against the refresh-rate setting before anything else.
- Panel
- Dynamic AMOLED 2X. This is an AMOLED panel, so dark mode reduces consumption for real — black pixels are switched off rather than backlit — and a static bright element left on screen for very long periods is the one wear risk this panel type has.
- Rear cameras
- 200.0 MP + 50.0 MP + 50.0 MP + 10.0 MP. A 200-megapixel main sensor produces very large files at full resolution, and it is the reason this model fills storage faster than almost anything else in the range. Samsung defaults to a binned lower-resolution output for exactly that reason — a storage complaint here is often a capture-resolution setting.
- Zoom
- Optical Zoom 3x and 5x, Optical quality Zoom 2x and 10x (Enabled by Adaptive Pixel sensor). Zoom range is the practical difference between models in this line. A close-up that will not focus at the long end is normally the telephoto's minimum focus distance rather than a fault — taking the same shot at 1x confirms it in seconds.
- Video
- UHD 8K (7680 x 4320)@30fps. Resolution and frame rate dominate how quickly video fills storage and how hard the phone works thermally — sustained 8K recording is the single most common reason a Galaxy camera stops mid-take and warns about temperature.
- Memory and storage
- 12GB RAM with a 256GB storage tier. RAM matters directly to one symptom: apps reloading when you switch back to them is memory pressure rather than a crash, and it is more likely on the lower-RAM configurations.
- SIM
- SIM 1 + SIM 2 / SIM 1 + eSIM / Dual eSIM. Three combinations are supported, and the default line for calls, for messages and for cellular data are three separate settings — crossing them produces calls arriving on one number while data or messages use another, with almost no indication that anything is wrong.
- Wi-Fi
- 802.11a/b/g/n/ac/ax/be 2.4GHz+5GHz+6GHz, EHT320, MIMO, 4096-QAM. This is Wi-Fi 7 hardware with 6 GHz support, so it can use bands an older phone on the same network cannot — which is worth knowing before concluding the router is at fault when one device performs differently from another.
- Bluetooth
- Bluetooth v5.4. Version affects range, reconnection behaviour and which accessory features are available — a newer accessory paired here operates at this version's capabilities rather than failing, which is regularly mistaken for a pairing fault.
- Connector
- USB Type-C. Note that a USB-C cable which fits is not necessarily rated for this phone's charging speed: USB-C carries several power profiles, and a data-oriented cable charges slowly or intermittently while seating perfectly.
- Samsung's own specification
- Samsung publishes the full specification for this model at samsung.com/uk/smartphones/galaxy-s25-ultra/specs/. Where any figure above matters to a decision, that page is the authority and this one is not.
- Biometric
- An in-display fingerprint reader, which looks through the screen. A thick or incompatible screen protector genuinely interferes with it, which is why unlock reliability often changes the day a protector is fitted rather than gradually.
- Modem
- 5G capable. In marginal 5G coverage the phone hands repeatedly between 5G and LTE, which costs more battery and generates more heat than settling on either — so the preferred-network setting is a real diagnostic lever rather than a preference.
- Charging
- Supports wireless charging. Coil alignment is tighter than it looks and a thick case, a metal plate or a card in the case defeats it entirely — so wireless charging failing while cable charging works is usually the case rather than the phone.
- Water resistance
- Rated water resistant, which is not waterproof and which degrades with age, drops and seal disturbance. The rating covers incidental exposure; it is not a guarantee, and moisture-detection warnings are deliberately conservative and can persist after the port feels dry.
- Platform
- Android, with a manufacturer interface layer over it. Battery optimisation and background-execution restrictions are applied per app and are far more aggressive than on iOS — which is why 'set this app to unrestricted' is a real fix here and has no equivalent elsewhere.
- Symptom boundary
- This record covers Samsung Galaxy S25 Ultra when it has no cellular service or data. A different symptom on the same hardware, or this symptom on a different Samsung product line, has its own record with its own causes and its own cited source.
Stop boundary
When this stops being a self-service repair
Continuing past any one of these costs more than the repair saves — in safety, in warranty, or in evidence a technician needs.
- !The account is suspended, the line has been ported away, or the eSIM profile needs reissuing — all carrier actions.
- !The phone is carrier-locked and needs unlocking, which only the original carrier can do.
- !The fault follows the phone rather than the SIM, after a drop or liquid exposure — that is the radio or the antenna.
- !Coverage at the address is genuinely poor and the practical answer is Wi-Fi calling or a signal booster rather than anything on the phone.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Where the manufacturer's article stops. Samsung publishes this as "Issues with mobile network connection on Samsung phone or tablet". Covers loss of cellular service and mobile data on a Galaxy phone, including network mode, SIM and network-settings reset. Probed 2026-08-21: title-verified. What that article does not carry is the model boundary — it is written for a product line, and SM-S938* is the scope applied here. Where a control label, terminal, indicator pattern or reset sequence differs on your unit, the manual for that exact model is the authority, not this page and not the article.
Exact questions
Common follow-ups
What size is the Galaxy S25 Ultra screen?+
Samsung lists 174.2mm (6.9" full rectangle) / 172.2mm (6.8" rounded corners), at 3120 x 1440 (Quad HD+). The two size figures are the full rectangle and the rounded-corner measurement — both are Samsung's own numbers, which is why this phone appears at two different sizes in different places.
Does the Galaxy S25 Ultra have a 120Hz screen?+
Yes, up to 120 Hz adaptive on a Dynamic AMOLED 2X panel. It is worth knowing for battery complaints specifically: a high refresh rate is one of the larger discretionary costs on this phone, and it is the first setting to check when runtime is disappointing.
Does dark mode save battery on the Galaxy S25 Ultra?+
Yes, genuinely — it uses an Dynamic AMOLED 2X panel, where black pixels are switched off rather than backlit. The saving is real though smaller than reducing brightness or refresh rate, which remain the larger levers.
What cameras does the Galaxy S25 Ultra have?+
200.0 MP + 50.0 MP + 50.0 MP + 10.0 MP, with optical zoom 3x and 5x, optical quality zoom 2x and 10x (enabled by adaptive pixel sensor). The 200-megapixel main sensor is also the reason this model fills storage quickly at full capture resolution — Samsung defaults to a binned output precisely because of that.
How much storage and RAM does the Galaxy S25 Ultra have?+
12GB RAM and a 256GB storage tier. The RAM figure is the one that matters for a specific symptom: apps reloading from scratch when you switch back to them is memory pressure rather than crashing, and it is more likely on lower-RAM configurations.
Does the Galaxy S25 Ultra support eSIM?+
Yes — Samsung lists SIM 1 + SIM 2 / SIM 1 + eSIM / Dual eSIM. Because more than one line can be active, check which line is set as the default for calls, for messages and for cellular data separately; those are three settings and crossing them is easy to do and hard to notice.
What Wi-Fi does the Galaxy S25 Ultra support?+
802.11a/b/g/n/ac/ax/be 2.4GHz+5GHz+6GHz, EHT320, MIMO, 4096-QAM. That is Wi-Fi 7 with 6 GHz, so it can use bands an older phone on the same network cannot — a useful thing to know before blaming the router when two devices behave differently.
Can the Galaxy S25 Ultra record 8K video?+
Yes — UHD 8K (7680 x 4320)@30fps. Bear in mind that resolution and frame rate dominate both how fast storage fills and how hard the phone works thermally, and sustained 8K is the most common reason a Galaxy camera stops mid-recording with a temperature warning.
What Bluetooth version is the Galaxy S25 Ultra?+
Bluetooth v5.4. Version affects range, reconnection and which accessory features are available — a newer accessory paired here runs at this version's capabilities rather than failing, which regularly gets misread as a pairing fault.
My phone says 'emergency calls only'. What does that mean?+
Usually that the phone has found a network and been refused by it — which points at the account or the SIM rather than at the radio. Check the account status with the carrier before doing anything to the phone; a suspended line and a failed radio look identical from the status bar.
How do I tell whether it is the phone or the network?+
Compare with another phone on the same carrier, same place, same time. Both struggling is coverage and nothing on your phone will change it. Only yours struggling narrows it to the phone, the SIM or the account — and the SIM-swap test separates those three definitively.
I have no service after switching phones.+
If you use an eSIM, that is the first thing to check. An eSIM does not travel with the handset the way a plastic SIM does — it has to be transferred or reissued, and a phone swap, a reset or a repair can leave the profile behind entirely.
Calls work but mobile data does not.+
That split is diagnostic: the radio and the account are both fine, because calls prove them. What remains is carrier settings and the APN. Check for a carrier settings update rather than editing the APN by hand, which is easy to get wrong and hard to reverse.
Should I edit the APN?+
Only against the carrier's own published values, and only after checking for a carrier settings update. A hand-edited APN that is slightly wrong produces a phone that half works, and it is much harder to diagnose afterwards than the original problem.
My data does not work on my second line.+
Check which line is set as the default for cellular data — it is a separate setting from the default voice line. Two-line phones make this easy to get wrong and give almost no indication that it is wrong.
Service keeps dropping in and out at home.+
Compare it against another phone on the same carrier there. If both are poor, that is coverage — and Wi-Fi calling is the practical answer rather than anything on the phone. Building construction matters a lot here: foil-backed insulation and low-emissivity glazing both attenuate heavily.
I bought the phone second-hand and the SIM does not work.+
Check the carrier-lock status in the phone's own settings. A handset locked to another carrier will show no service with a new SIM regardless of configuration, and only the original carrier can unlock it.
Would a signal booster help?+
Where the problem is genuinely weak coverage at a fixed address, yes. Where the problem is the account, the SIM or a manual network selection, no — and those are cheaper to exclude first. Establish that another phone on the same carrier is equally poor before spending anything.
Does this answer apply to every Samsung model?+
No. It is scoped to SM-S938*. Samsung Galaxy family; S Pen, foldable display, DeX, USB moisture and One UI features vary by exact model.
What should I record before troubleshooting no service or cellular data?+
Record the complete model identifier, exact message or indicator, software/firmware where visible, the operating stage and what still works.
Why is a factory reset not the first step?+
A reset can erase accounts, networks, maps, schedules or preferences without distinguishing no service, cellular data. The ordered checks preserve that evidence.
When should I stop and use qualified service?+
Use the most reliable available path for emergency calls; do not delete the only eSIM without a replacement plan.
Answer for the exact device and software version shown above.