Last checked: 26 June 2026
If you have no signal after SIM swap, your new SIM may still be activating, the swap may not have completed, your phone may not be registering on the network, or the account may need provider support. Start with the checks below before retrying codes or assuming the SIM swap failed.
A phone that says No Service, SOS, Emergency calls only, Searching, or Not registered on network is not properly connected to the mobile network. Apple’s support guidance says “No Service” or “Searching” means the device is not connected to a mobile network, and recommends trying Airplane Mode, restarting, checking account status, coverage, outages, device barring, and network settings with the provider. (Apple Support)
Quick Fixes to Try First
| Check | What to do | What it tells you |
|---|---|---|
| Activation time | Wait for the provider’s activation window before repeating the swap. | If the SIM is still activating, signal may return without another request. |
| Airplane Mode | Turn Airplane Mode on for at least 15 seconds, then turn it off. | This forces the phone to search for the mobile network again. (Apple Support) |
| Restart | Switch the phone off, remove and reinsert the SIM, then restart. | This checks whether the SIM was seated badly or the phone failed to refresh. |
| SIM slot | On a dual-SIM phone, place the swapped SIM in SIM slot 1 and make sure that line is turned on. | Dual-SIM settings can leave the correct line disabled. Apple recommends checking that the mobile line is switched on for Dual SIM devices. (Apple Support) |
| Coverage | Move to a place where the same network usually has signal. | Poor coverage can look like a failed SIM swap. |
| Another phone | Test the SIM in another compatible phone. | If it works there, the issue may be your phone, SIM tray, or settings. If it fails there too, contact the network. |
| Provider status | Contact the provider if the activation time has passed. | Only the network can confirm whether the SIM swap completed, failed, was barred, or needs verification. |
Do not keep trying random SIM swap codes while the phone has no signal. USSD usually needs a working mobile network connection, so a code can time out or fail even when the code itself is correct.
Why This USSD Problem Happens
The SIM swap may still be activating
No signal immediately after a SIM swap does not always mean the swap failed. Some swaps take time to activate.
Vodacom’s official SIM swap guidance says a prepaid SIM swap may take up to 3 hours for the new SIM to activate, while contract SIM swaps may take about 2 to 24 hours. (VodacomNow) Cell C’s official FAQ says users should wait at least 2 hours before inserting the new SIM card after a SIM swop route. (Cell C)
If you are still inside the provider’s activation window, wait before starting another request. Repeating the process too soon can make troubleshooting harder.
The SIM may not be correctly linked to the number
A SIM swap has to move your old number to the new SIM. If the swap was interrupted, not verified, not completed, or blocked for security reasons, the SIM may show no service. MTN’s PayAsYouGo terms say SIM swaps are subject to RICA compliance, the old number still being active and available on MTN’s systems, and other conditions. (MTN)
The phone may not be registering on the network
The problem may be the phone rather than the swap. The device may need a restart, the SIM may be loose, the mobile line may be turned off, the network settings may need to refresh, or the device may be barred. Apple’s guidance says users should contact the network provider to verify that the account is active, the area has coverage, there are no outages, and the device is not blocked or barred from mobile service. (Apple Support)
The wrong network route may have been used
A SIM swap must be done through the provider that owns the number. A Vodacom, MTN, Telkom, or Cell C process cannot be used interchangeably. If you bought the wrong SIM, used the wrong support route, or tried a menu path for a different network, the swap may not complete.
The phone may show no signal because of fraud or illegal porting
If you did not request a SIM swap, sudden signal loss is urgent. ICASA warns that signal loss can indicate SIM-swap fraud or number porting, and says users should contact their service provider immediately if they lose signal permanently. (icasa.org.za) SABRIC also warns that loss of mobile connectivity where you are usually connected can indicate an illegal SIM swop, and advises contacting the mobile network operator as soon as possible. (sabric.co.za)
Provider-Specific Checks
Use the provider route that matches your number. If the phone has no signal, use Wi-Fi, another phone, WhatsApp support, the provider app, website support, or a store instead of relying on USSD.
| Provider | What to check first | What to do next |
|---|---|---|
| Vodacom | Check whether you are still inside the activation window. | Vodacom says prepaid SIM swaps may take up to 3 hours to activate, while contract swaps may take about 2 to 24 hours. If you did not request the SIM swap, Vodacom says you can stop the request before it is processed by calling 135. (VodacomNow) |
| MTN | Check that the number is RICA-compliant, active, available, and not restricted. | MTN’s terms say a SIM swap is subject to RICA compliance and other account conditions. Its official help result also lists *135*3# from the new SIM as a SIM swap route, but use customer care or the MTN app if the SIM has no signal. (MTN) |
| Telkom | Use WhatsApp or customer support if the SIM has no signal. | Telkom says SIM swaps can be done via its WhatsApp self-service channel by sending a WhatsApp to 081 160 1700, and notes that store SIM swaps are charged. (Telkom) |
| Cell C | Check whether you inserted the SIM too early. | Cell C says users can request a SIM Swop through Self-Service IVR, a Cell C store, or an agent route, and should wait at least 2 hours before inserting the new SIM card. (Cell C) |
For the broader SIM swap process, read how to do SIM swap South Africa. If the swap failed, timed out, or did not activate, read SIM swap not working. If the signal loss was unexpected or suspicious, go straight to SIM swap fraud South Africa.
When to Use an App, Website, or Customer Care Instead
Use an app, website, WhatsApp support, customer care, or a store instead of USSD when:
- the phone says No Service, SOS, Emergency calls only, or Not registered on network;
- the activation time has passed and signal has not returned;
- the new SIM is not detected in any phone;
- the phone detects the SIM but will not register on the network;
- you did not request the SIM swap;
- your banking OTPs, WhatsApp, email, or mobile banking access stopped at the same time;
- you received an SMS about a SIM swap or port request you did not authorise;
- the provider says the number is barred, suspended, not RICA-compliant, or still pending.
Step-by-step escalation route
- Stop retrying codes. If the phone has no signal, USSD may not work. Retrying unrelated codes will not fix a network registration problem.
- Wait for the provider’s activation period. If your provider says activation can take several hours, wait before assuming failure.
- Restart and reseat the SIM. Switch the phone off, remove the SIM, check that it is correctly placed, reinsert it, and switch the phone on again.
- Toggle Airplane Mode. Turn it on for at least 15 seconds, then turn it off. This is a recommended reconnect step for mobile network issues. (Apple Support)
- Check dual-SIM settings. Make sure the swapped SIM line is turned on and selected for calls, SMS, and mobile data.
- Test another phone. If the SIM works in another phone, the issue may be your device settings, SIM slot, or handset. If it does not work in another phone, the provider needs to check the SIM swap and account.
- Contact the network from another channel. Use Wi-Fi, online chat, WhatsApp, another phone, or a store. Ask the provider to confirm whether the swap is complete, whether the number is active, whether the SIM is linked, whether the account is barred, and whether there is a network outage.
- Get a reference number. If the provider cannot resolve it immediately, ask for a support reference number.
- Escalate if unresolved. ICASA says telecommunications complaints must first be lodged with the service provider, with a reference number, and the provider must be allowed 14 working days to resolve the complaint before escalation to ICASA if unresolved or unsatisfactory. (icasa.org.za)
For the correct support route, use mobile network customer care numbers.
Safety Checks Before You Continue
No signal after SIM swap can be normal during activation, but it can also be a fraud warning.
Act immediately if:
- your old SIM lost signal and you did not request a SIM swap;
- you received a SIM swap or porting notification you did not authorise;
- someone told you to switch your phone off, ignore a SIM swap message, or share an OTP;
- your banking OTPs stopped arriving;
- your WhatsApp or social accounts suddenly ask you to re-register;
- you receive unexpected password reset messages.
Vodacom warns that sudden loss of connectivity or failure to receive calls and texts should not automatically be treated as a handset or network problem, and recommends contacting customer care immediately to check for possible SIM swap activity. (VodacomNow) ICASA also advises users not to give consent through unsolicited links, not to respond to requests for personal or confidential information, and to contact the provider if signal is lost permanently. (icasa.org.za)
Do not share your OTP, banking PIN, app password, ID photo, selfie verification, or SIM serial number with anyone who contacts you unexpectedly.
Related Guides
- How to do SIM swap South Africa
- SIM swap fraud South Africa
- Mobile network customer care numbers
- SIM swap not working
FAQs
Why is no signal after SIM swap happening?
It may be because the SIM swap is still activating, the new SIM was inserted too early, the SIM is not linked correctly, the account needs verification, the phone is not registering on the network, or the number has been barred or restricted. If you did not request the SIM swap, sudden signal loss should be treated as urgent because ICASA and SABRIC both warn that signal loss can indicate SIM-swap fraud or illegal number porting. (icasa.org.za)
Does this mean the code has changed?
Not always. The code may still be correct, but USSD can fail when the phone has no network connection. It can also fail if the SIM swap is pending, the account is restricted, the wrong provider route was used, or the provider requires extra verification.
Can I fix it without calling customer care?
Sometimes. Wait for the activation period, restart the phone, reseat the SIM, toggle Airplane Mode, check dual-SIM settings, and test the SIM in another phone. If the SIM still has no service after the activation window, contact the provider because only the network can check the swap status and account restrictions.
Should I use the app instead of USSD?
Use the app, website, WhatsApp support, online chat, another phone, or a store if the SIM has no signal. USSD usually needs a working mobile network connection, so it may not help while the phone says No Service.
What should I prepare before contacting support?
Prepare your ID or passport, affected cellphone number, new SIM packaging or SIM serial number, the time and date of the SIM swap request, error messages, and any previous reference numbers. Do not send these details through unofficial links or to someone who contacted you unexpectedly.
Are there costs, limits, or eligibility rules?
They depend on the provider, account type, and support route. Vodacom notes that contract SIM swaps may have a SIM card activation fee, while Telkom says WhatsApp self-service SIM swaps are at no cost and store SIM swaps are charged. (VodacomNow) Always check the provider’s current page before publishing fees, limits, activation times, or menu paths.