Great — below is a more detailed, comprehensive expansion of each section from the article you were shown earlier. I’ve added practical examples, troubleshooting tips, carrier caveats, security advice and extra context so a reader of any technical level can follow, test and be confident they’ve fully controlled call forwarding on their device. Written in the voice of a UK tech blogger with a decade covering mobile tech and networks.
What is Call Forwarding?
Call forwarding (also called call diversion) is a network-level feature that redirects incoming voice calls to another telephone number. It’s implemented by your mobile operator, not just the phone, which is why you can control it both from device settings and by using network codes.
More detail on the four main forwarding types
- Always forward (unconditional): every incoming call is immediately sent to the specified number — the caller never rings your handset. Use when you don’t want calls on a device (e.g., temporary number change).
- Forward when busy: activated only if your line is already in use. The network detects the busy state and sends the call to the forwarded number or voicemail.
- Forward when unanswered (no answer): triggers after a set number of rings that you can sometimes change (e.g., 15–30 seconds). Used by people who want voicemail or a colleague to pick up if they can’t answer.
- Forward when unreachable: used when your device is off, in airplane mode, or out of network coverage. Useful when you travel and want calls routed to a local number or to a receptionist.
Why networks implement call forwarding
- To provide voicemail and unified messaging services.
- To offer business continuity features (calls sent to office if home phone offline).
- As part of personal convenience features (forward to family member while travelling).
How forwarding lives at two places
- Device-level: smartphone settings may show and toggle forwarding for “Always forward” and sometimes others.
- Network-level: operator keeps forwarding rules for conditional forwards — this is why dial codes are necessary to query and clear them reliably.
How to Check Call Forwarding on Any Phone
There are two reliable ways to check forwarding: using the phone’s menus and using network dial/USSD codes. I’ll explain both and when to prefer one over the other.
Using built-in phone settings — what to expect and pitfalls
Android (stock and OEM skins)
Where to look:
- Phone app → Settings → Call settings → Additional settings / Advanced settings → Call forwarding (or Calling accounts → SIM → Call forwarding).
What you’ll see: - A list of forwarding types and either “Not set” or the number that calls forward to.
Pitfalls: - Some Android skins (MIUI, One UI) hide forwarding settings in different places. If you have dual-SIM, each SIM has separate forwarding rules.
- Settings may only display the “Always forward” number; conditional forwarding may not appear even when active (because operator stores it).
Tips:
- If you don’t see a forwarding entry but suspect forwarding, use the dial codes described below.
- On dual-SIM phones, test both SIMs — forwarding can be active on one and not the other.
iPhone (iOS)
Where to look:
- Settings → Phone → Call Forwarding.
What you’ll see: - A single toggle and the forwarding number for unconditional forwarding.
Limitations: - iOS generally shows only unconditional forwarding in its UI. Conditional forwarding (busy/unanswered/unreachable) is a network-level setting and will not show here.
Feature phones and basic handsets
- Feature phones usually have a Call Settings → Call diversion menu that lists the four types, but menu names vary.
- When in doubt, use dial codes.
Using USSD / network dial codes — the most reliable method
These codes query the operator’s network and return exact status. They are standardized for GSM networks but some carriers deviate.
Common status codes (query):
- *#21# — show unconditional (all) forwarding status
- *#61# — show no-answer forwarding status
- *#62# — show unreachable forwarding status
- *#67# — show busy forwarding status
Common cancellation/deactivate codes:
- ##21# — cancel unconditional forwarding
- ##61# — cancel no-answer forwarding
- ##62# — cancel unreachable forwarding
- ##67# — cancel busy forwarding
- ##002# — cancel all forwarding (handy “nuclear” option)
Practical notes:
- After dialing a query code you usually receive an on-screen message that lists forwarding numbers and conditions.
- If a code returns an error or does nothing, your provider may use different codes — contact them or check their support page. Some carriers require you to manage forwarding through your online account.
How to Disable Call Forwarding on Any Phone — step-by-step, with safety checks
Below I expand on step-by-step methods and include verification steps so you can be certain forwarding is off.
Disable via phone settings (Android & iPhone) — step-by-step
Android
- Open Phone → Settings → Call settings → Call forwarding.
- Select the SIM you want to check.
- For each forwarding type that lists a number, open it and choose “Turn off” or “Disable.”
- After disabling, restart your phone (optional but recommended) and dial *#21# (or use *#67# etc.) to verify via the network.
iPhone
- Settings → Phone → Call Forwarding.
- Toggle Call Forwarding off.
- For conditional forwards (that iOS won’t show), dial the USSD cancellation codes above or call your carrier to confirm.
Feature phone
- Navigate to Call Settings → Call diversion and choose “Cancel” for each active rule. Then test from another phone.
Disable using USSD codes — quick and reliable
- To cancel everything at once: dial ##002# and press call (this deactivates all forwarding types on most GSM networks).
- To cancel specific types, use the specific ##XX# codes mentioned earlier (example: ##67# to cancel busy forwarding).
- Wait for the confirmation message from the network — it usually confirms “Call forwarding disabled.”
Verification:
- After cancellation, dial the query codes (*#21#, *#67#, etc.) to confirm the operator reports “Not forwarded” or equivalent.
- Optionally ask a friend to call you to ensure the phone rings normally.
Practical tests to confirm forwarding is off
- Two-phone test: Call your phone from a different number and watch behaviour. If it rings, forwarding likely disabled. If call goes straight to another number or voicemail, forwarding remains active.
- Check call logs: If a call was forwarded previously you may see missed calls or forwarding-related entries in carrier call logs (carrier portal).
- Voicemail behaviour: If calls go directly to voicemail unexpectedly, that can indicate conditional forwarding to voicemail. Toggle forwarding off and test.
Why your call forwarding might be active without your knowledge —
- Deliberate prior setup: You or someone else set it in the past and forgot.
- Voicemail / operator services: Some voicemail configurations implement forwarding at the operator level.
- SIM moved to another handset: Another phone might have changed settings (e.g., a support tech or family member).
- Carrier defaults or changes: Operators sometimes enable services during plan changes or porting numbers between carriers.
- Apps and third-party services: Some apps (business or virtual number apps) can enable call diversion.
- SIM cloning or compromise (rare but serious): If forwarding appears to a number you don’t recognise, treat it as suspicious — see security section below.
When you should not disable call forwarding — real world scenarios
- Business lines: If your workplace routes calls to a receptionist, disabling could cause missed calls.
- Voicemail dependency: In some countries voicemail relies on conditional forwarding — disabling might break voicemail.
- Family or emergency routing: If you forward to a family member while travelling, disabling removes that safety net.
- Call-centre numbers or services: Some customer services use forwarding as part of call distribution.
Before disabling, verify whether a service you rely on will be affected. If uncertain, temporarily disable and test or consult your carrier.
What to do if call forwarding keeps turning back on — detailed troubleshooting
If you cancel forwarding but it reappears:
- Restart and retest: Restart the handset and check again.
- Remove and reinsert SIM: This can force the network to refresh.
- Reset network settings: Android: Settings → System → Reset options → Reset Wi-Fi, mobile & Bluetooth. iPhone: Settings → General → Reset → Reset Network Settings. (This removes saved Wi-Fi and Bluetooth profiles.)
- Use ##002#: Cancel all forwarding at the network level.
- Check installed apps: Look for call-management, VoIP, or business apps that may enable forwarding. Uninstall or disable them temporarily.
- Change SIM PIN / secure account: If you suspect account compromise, set or change SIM PIN and change carrier account passwords.
- Contact your carrier: Ask them to check forwarding rules on their end and to disable operator-level forwards. They can often remove forwarding or investigate recurring activation.
- Factory reset (last resort): If all else fails and you suspect device-level interference, backup data and factory reset the handset.
Security and privacy considerations — signs of unauthorised forwarding and what to do
Signs of unauthorised forwarding
- Calls are consistently redirected to an unfamiliar number.
- You see forwarding entries to numbers you don’t recognise.
- Your phone doesn’t ring but calls reach voicemail or another device.
- SIM or carrier account notifications you didn’t request.
Immediate steps if you suspect unauthorised forwarding
- Dial ##002# to disable all forwarding.
- Change your mobile account password and any linked account passwords.
- Set or change your SIM PIN (secure the SIM so it can’t be moved to another phone without a PIN).
- Contact your carrier to report potential fraud — they can block/trace forwarding changes.
- Ask for account activity logs (the carrier may provide recent management actions).
- If the issue persists, consider getting a replacement SIM with the same number (carrier can do this) and request a security audit.
Costs, roaming and business caveats — what to watch for
- Charges: Forwarded calls may incur charges. Depending on your plan, forwarding can be free (operator-level to voicemail) or charged at call-forwarding rates (the network calls the forwarded number on your behalf). Check your contract.
- Roaming: If you forward to an overseas number while roaming, costs can be substantial. Always verify rates while travelling.
- Business numbers and DID services: If you use virtual number providers (DID), forwarding rules are managed at provider portals and may bypass your handset settings.
Quick reference: Common GSM codes (summary)
- Check status: *#21#, *#61#, *#62#, *#67#
- Cancel specific: ##21#, ##61#, ##62#, ##67#
- Cancel all forwarding: ##002#
Note: Not all operators accept these commands — if a code fails, contact your carrier.
Final checklist — make sure forwarding is really off
- Use device settings to disable visible forwarding.
- Use ##002# to clear operator-level forwards.
- Verify with *#21#, *#61#, *#62#, *#67#.
- Ask a friend to call and confirm the phone rings.
- Check your account or carrier portal for forwarding entries.
- If forwarding reappears, change SIM PIN and contact the carrier.
