Direct answer
For the Samsung Galaxy A35 5G, carrier service, selected line, account activation, recipient-specific block and messaging service should be separated. First, test a normal call, SMS and another contact with Wi-Fi off.
What this covers
- Samsung Galaxy A35 5G (SM-A356*)
- Samsung Galaxy family; S Pen, foldable display, DeX, USB moisture and One UI features vary by exact model.
- The specific fault this record addresses: cannot make calls or send messages
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
No usable service in the first place
What separates it No calls and no SMS, with the status bar showing no service or emergency only. Everything else on this page assumes service exists.
How to confirm Check the signal indicator and whether data works. Where there is no service at all, that is the problem to solve first.
- 2
The account is suspended or the line was ported
What separates it Emergency calls only on a phone that is otherwise perfect, often on a billing date. It looks identical to a hardware fault.
How to confirm Check the account status with the carrier before anything phone-side.
- 3
The number is blocked, or the phone is silencing unknown callers
What separates it Specific people cannot reach you, or calls go straight to voicemail without ringing. Both platforms offer silencing of unknown numbers, and block lists accumulate.
How to confirm Check the block list and any silence-unknown-callers setting. This produces a phone that appears to work perfectly and misses specific people.
- 4
Call forwarding was left on
What separates it Calls never arrive and go somewhere else entirely, often after a trip abroad or a voicemail setup. Forwarding survives until it is switched off.
How to confirm Check the call forwarding setting, which is easy to leave enabled and gives no indication that it is.
- 5
A focus mode silencing calls
What separates it Calls arrive but the phone does not ring, on a schedule. Focus and bedtime modes both do this deliberately.
How to confirm Check for an active focus mode and its allowed-callers list.
- 6
Wi-Fi calling on a poor Wi-Fi network
What separates it Calls fail or break up at home where cellular is fine, or the reverse. Wi-Fi calling prefers Wi-Fi even when the Wi-Fi is worse than the cellular signal.
How to confirm Turn Wi-Fi off and retry the same call. A clear difference identifies the path.
- 7
RCS or an internet messaging service rather than SMS
What separates it Messages fail to one person and work to everyone else, or fail on Wi-Fi and work on cellular. Modern messaging silently chooses between several transports.
How to confirm Send the same message as a plain SMS where the app allows it. Success there localises the fault to the internet transport rather than the network.
- 8
The recipient's number is stored in the wrong format
What separates it Messages fail to contacts saved without a country code, particularly after travelling or changing country.
How to confirm Compare a failing contact's stored number against the full international format.
- 9
A second line handling voice or messaging unexpectedly
What separates it Calls come in on one number and messages go out on another. Default lines for voice and messaging are separate settings.
How to confirm Check which line is the default for calls and which for messages.
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.
- Whether calls fail, messages fail, or both — and whether it is to everyone or to specific people.
- The signal indicator and whether mobile data works, which establishes whether there is service at all.
- Whether it fails on Wi-Fi, on cellular, or both.
- Whether calls ring and are missed, or never arrive at all — those are different failures.
- Whether call forwarding, a block list, or a silence-unknown-callers setting is active.
- Whether the affected contacts are stored in full international format.
- The account status with the carrier.
Establish whether there is service at all
ReversibleNo service, or emergency calls only, makes everything else on this page irrelevant. 'Emergency calls only' in particular usually means the phone found a network and was refused by it, which is an account matter rather than a phone one.
Determine whether it is everyone or specific people
ReversibleEveryone points at service, the account or a system setting. Specific people points at a block list, a contact's stored number format, or the messaging transport. These share no further steps.
Check the block list and silence-unknown-callers
ReversibleBoth produce a phone that appears to work perfectly while specific people cannot reach you, and both accumulate quietly. Calls going straight to voicemail without ringing is the classic signature.
Check call forwarding
ReversibleForwarding left on after a trip abroad or a voicemail setup sends calls somewhere else indefinitely, with no indication on the phone that it is doing so. This is a five-second check that resolves an otherwise baffling symptom.
Turn Wi-Fi off and retry the same call
ReversibleWi-Fi calling prefers Wi-Fi even when the Wi-Fi is worse than the cellular signal available. Calls that fail at home and work elsewhere, or the reverse, are identified by this single test.
Send the same message as a plain SMS
ReversibleModern messaging chooses silently between RCS, an internet service and SMS. Success as plain SMS localises the fault to the internet transport, which is a completely different investigation from the cellular network.
Check the contact's stored number format
ReversibleA number saved without a country code fails in ways that look like a network fault, particularly after travelling or changing country. Comparing a failing contact against the full international format is quick and specific.
Check for an active focus mode
ReversibleCalls that arrive without the phone ringing, on a schedule, are a focus or bedtime mode with an allowed-callers list — not a call failure. The distinction matters because nothing about the network is involved.
Confirm which line handles calls and which handles messages
ReversibleDefault lines for voice and messaging are separate settings, and getting them crossed produces calls arriving on one number while messages leave from another. It is easy to set wrong and gives almost no indication.
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-A356*. Samsung Galaxy family; S Pen, foldable display, DeX, USB moisture and One UI features vary by exact model.
- Tier — mid-range (A-series)
- A mid-range Galaxy below the A55/A54 — no S Pen, no wireless charging, a modest chip. Tier characteristics, not faults.
- One UI / Android
- One UI over Android, shorter update window. eSIM varies by region.
- IP67
- Water/dust resistant (IP67). Fast wired charging.
- Connector
- USB-C. A cable that fits is not necessarily a cable rated for this phone's charging speed — USB-C carries several power profiles and a cable built for data will charge slowly or intermittently while seating perfectly.
- SIM
- Carries an eSIM. An eSIM does not travel with the handset the way a plastic SIM does: a phone swap, a factory reset or a repair can leave the profile behind, and restoring it is a carrier action rather than a phone setting.
- SIM
- Supports two active lines. The default line for calls, for messages and for cellular data are three separate settings, and getting them crossed produces calls arriving on one number while data or messages use another — with almost no indication that anything is wrong.
- 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 A35 5G when it cannot make calls or send messages. 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 or the line has been ported away — a carrier matter that no phone-side change addresses.
- !There is no service at all and another phone on the same carrier works in the same place.
- !Calls connect and neither party can hear the other after the microphone and speaker have both been excluded.
- !Emergency calling itself is unreliable, which should be treated as urgent rather than troubleshooted at leisure.
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 "Galaxy phone is unable to make or receive calls". Samsung's article for a Galaxy phone that cannot place or receive calls, covering network, SIM, blocking and call-setting causes. 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-A356* 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
My Samsung Galaxy A35 storage fills up and it slows down.+
Mid-range phones ship with less storage and a modest chip, so a nearly full phone slows noticeably. Free space by clearing cached files, offloading photos/videos to cloud or a microSD card (the A-series usually supports one, unlike flagships), and removing unused apps. Keeping 10–20% storage free and the software updated keeps it responsive. The slowdown is storage/tier, not a hardware fault.
Calls go straight to voicemail without ringing.+
Check three things: call forwarding, the block list, and any silence-unknown-callers setting. All three produce exactly this, all three leave the phone looking perfectly healthy, and all three are easy to leave switched on without knowing.
Only one person cannot reach me.+
That rules out service, the account and the phone — all of which would affect everyone. What remains is a block list entry, that contact's stored number format, or the messaging transport being used for them specifically.
Messages fail to one contact and work to everyone else.+
Send the same message as a plain SMS if the app allows it. Modern messaging silently chooses between RCS, an internet service and SMS, and success as plain SMS localises the fault to the internet transport rather than the network. Also check that their number is stored in full international format.
Calls break up at home but are fine elsewhere.+
Turn Wi-Fi off and retry. Wi-Fi calling prefers Wi-Fi even when the Wi-Fi is worse than the cellular signal available, so a poor home network can produce worse calls than no Wi-Fi at all. One test identifies it.
My phone says emergency calls only.+
That usually means the phone found a network and was refused by it, which points at the account or the SIM rather than the radio. Check the account status with the carrier first — a suspended line and a failed radio look identical from the status bar.
Calls arrive but the phone does not ring.+
Check for an active focus mode and its allowed-callers list. Focus and bedtime modes silence calls deliberately and on a schedule, and nothing about the network or the call itself is involved.
I cannot call anyone after coming back from abroad.+
Check call forwarding first — it is commonly enabled while travelling and left on afterwards, and the phone gives no indication. Then check that the network selection has been returned to automatic rather than left on a manual foreign network.
Messages send on Wi-Fi but not on cellular.+
That points at the internet messaging transport rather than SMS. The two use completely different paths, and a transport that works on one connection and not the other is describing the network rather than the phone or the recipient.
Calls connect but nobody can hear me.+
That is a microphone problem rather than a calling one — and the first thing to check is whether a Bluetooth accessory is connected somewhere, because it takes the call's microphone with it. Record a voice note to test the microphone alone.
Does this answer apply to every Samsung model?+
No. It is scoped to SM-A356*. Samsung Galaxy family; S Pen, foldable display, DeX, USB moisture and One UI features vary by exact model.
What should I record before troubleshooting calls or messages?+
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 calls, messages. The ordered checks preserve that evidence.
When should I stop and use qualified service?+
Use another reliable path for urgent or emergency communication.
Answer for the exact device and software version shown above.