Call Forwarding Not Working? 7 Reasons Why (And How I Fixed Each One)

Okay, so you dialed **21*08012345678# and… nothing.

Or maybe you got “CONNECTION PROBLEM OR INVALID MMI CODE” and now you’re staring at your phone like it personally betrayed you.

I get it. A week ago, I spent 20 minutes trying to forward a new personal line, and it just kept failing. Turns out I was making one of the most common mistakes (Problem #1 below), and once I fixed it, took 15 seconds.

Here’s what’s actually wrong and how to fix it. Not theory—just the stuff that works.

Quick Diagnostic: Which Problem Do You Have?
❯

Before we dive in, figure out which scenario matches yours:

• Code not working at all? → Problem #1 or #5
• “CONNECTION PROBLEM” error? → Problem #5 (jump there first)
• Spinning wheel that never finishes? → Problem #6
• Works sometimes but not always? → Problem #4 or #7
• Just says “failed” with no explanation? → Problem #2 or #3

 

Got it? Let’s fix this.

 

Problem #1: You’re Using the Wrong Number Format

This is embarrassing but I did over ten times.

What’s Happening
❯

You dialed **21*8012345678# (missing the zero) or *21+2348012345678# (added the country code when you shouldn’t).

 

The Fix
❯

MTN, Airtel, Glo, 9mobile—they all want the number in this exact format:

• Start with zero (08012345678, not 8012345678)
• 11 digits total for Nigerian numbers
• No country code (+234)
• No spaces or dashes

 

Sounds simple but apart from myself, I’ve also seen people make this same mistake. The phone just sits there. No error. No confirmation. Nothing.

Try it again with the correct format. Press call. Wait for the SMS confirmation.

Still not working? Your carrier might require the country code format. Try *21+2348012345678# instead. MTN usually doesn’t need it, but I’ve seen some Airtel lines that do.

 

Problem #2: Your Network Signal Is Terrible

This one’s obvious but everyone ignores it.

What’s Happening
❯

Call forwarding setup needs to communicate with your carrier’s network. If you’re in an elevator, or that one corner of your house where nothing works—it won’t register.

 

The Fix
❯

1. Check your signal bars (need at least 3/5)
2. Move to a window or outside
3. Turn on and off Airplane Mode (wait 10 seconds between)
4. Try again

 

I was helping a friend with this last month. Glo signal in that building? One bar. Couldn’t activate forwarding no matter what I tried. Walked outside. Five bars. Code worked instantly.

If you’re consistently in a low-signal area, you have two options:

• Always set up forwarding when you have good signal
• Get a virtual number that works over internet (doesn’t need cellular signal)

 

Speaking of which, I switched my business line to PressOne virtual number specifically because of this. Can change forwarding from the app even when I have zero bars. But I’m getting ahead of myself.

 

Problem #3: Do Not Disturb Mode Is Blocking Everything

This drove me insane for a week before I figured it out.

What’s Happening
❯

Your Do Not Disturb settings might be interfering with call forwarding activation. Or—and this is the sneaky one—you have Call Barring active which blocks forwarding entirely.

 

The Fix for Do Not Disturb
❯

On iPhone:

1. Settings → Focus → Do Not Disturb
2. Turn it OFF completely
3. Try your forwarding code again
4. Turn DND back on after (forwarding will still work)

On Android:

1. Settings → Sound → Do Not Disturb
2. Turn it OFF
3. Try forwarding code
4. Turn it back on

 

The Fix for Call Barring
❯

Dial **#33# and press call. This shows if call barring is active.

If it says barring is ON, dial **35*0000# (default PIN is usually 0000) to turn it off.

Then try your forwarding code again.

 

How I Discovered This:

Spent a week troubleshooting. Finally checked call barring—it was ON. I had activated it months ago for international calls and forgot about it. Deactivated it, forwarding worked immediately.

 

Problem #4: You’re Using the Wrong Forwarding Code (Most Common!)

I see this mistake every time.

What’s Happening
❯

You want calls to forward when you don’t answer, but you used *21 (forward ALL calls). Or you want all calls forwarded, but you used *61 (forward only unanswered calls). The code worked—you just activated the wrong type.

 

Here’s What Each Code Actually Does:

**21*number# = Forward EVERY call immediately

Your phone never rings. All calls go straight to the other number.

Use when: You want zero calls on your original line.

 

**67*number# = Forward when you’re on another call (busy)

Your phone rings normally, but if you’re already talking, the second call forwards.

Use when: You can’t take multiple calls at once.

 

**61*number# = Forward when you don’t answer (after 15-20 seconds)

Your phone rings first. If you don’t pick up, THEN it forwards.

Use when: You want a backup—this is what most people actually want.

 

**62*number# = Forward when your phone is off or unreachable

Only forwards if your phone is dead, switched off, or no signal.

Use when: Backup for emergencies only.

I once wondered why my MTN line wasn’t ringing. Turns out I had activated *21 thinking it meant “forward when busy.” Nope. It meant “forward everything.” Changed it to *61 and problem solved.

 

Quick Test:

After activating forwarding, call yourself from another phone. Does your original phone ring? If yes, you used *61, *62, or *67. If no, you used *21.

If you activated the wrong one:

1. Dial ##002# to turn OFF all forwarding
2. Dial the correct code for what you actually want
3. Test it

 

Problem #5: “CONNECTION PROBLEM OR INVALID MMI CODE” Error (The Worst One)

This error message. This useless error message that tells you nothing.

I’ve encountered this more than a dozen times in the past year. Here’s what actually works.

What’s Happening
❯

Your phone can’t communicate with the carrier’s network properly. Could be temporary network congestion, could be your phone’s mobile data interfering, could be a dozen things.

 

Fix #1: The Network Reset (Works 60% of the Time)
❯

On Android:

1. Settings → System → Reset Options
2. Reset Wi-Fi, mobile & Bluetooth
3. Tap “Reset Settings”
4. Phone will restart
5. Try your code again

On iPhone:

1. Settings → General → Transfer or Reset iPhone
2. Reset → Reset Network Settings
3. Enter your passcode
4. Confirm
5. Try your code again

⚠️ Warning: This will delete all saved Wi-Fi passwords. Write them down first.

 

Fix #2: The Airplane Mode Dance (Works 30% of the Time)
❯

1. Turn ON Airplane Mode
2. Wait 30 seconds (seriously, wait the full 30)
3. Turn OFF Airplane Mode
4. Wait for signal to come back
5. Try your code immediately

 

Fix #3: The SIM Card Removal (Works for Stubborn Cases)
❯

1. Power off your phone completely
2. Remove the SIM card
3. Wait 1 minute
4. Reinsert SIM card
5. Power on
6. Try your code

 

Fix #4: Disable Mobile Data Temporarily
❯

Sometimes mobile data interferes with USSD codes.

1. Turn off Mobile Data
2. Try your forwarding code
3. Turn Mobile Data back on

 

Had an experience with this a couple of days ago on an Airtel line. Tried everything. Network reset didn’t work. Airplane mode didn’t work.

Called Airtel customer service (111), as usual it took them forever to connect me with a customer service rep.

Finally removed the SIM card, cleaned the contacts with my shirt (yeah, I know), put it back in. Worked.

Sometimes it’s just that simple.

 

Still Getting the Error?

Your carrier might have an issue on their end. Call them:

• MTN: 180
• Airtel: 111
• Glo: 121
• 9mobile: 200

 

Tell them exactly: “I’m getting INVALID MMI CODE error when trying to activate call forwarding.” They can check if the service is enabled on your account.

 

Problem #6: The Forwarding Setup Screen Is Stuck (Spinning Wheel)

You tapped “Call Forwarding” in your phone settings and now it’s just… spinning. Forever.

This happens more on iPhones than Android in my experience.

What’s Happening
❯

Your phone is trying to contact your carrier to get current forwarding settings but the request is timing out.

 

The Fix for iPhone
❯

1. Force close the Settings app:
   • Swipe up from bottom (or double-click home button)
   • Swipe up on Settings to close it
2. Open Settings again
3. If still spinning, restart your iPhone
4. If STILL spinning, skip the Settings menu entirely:
   • Just use the USSD codes (**21*number#)
   • They work even when the settings screen doesn’t

 

The Fix for Android
❯

1. Settings → Apps → Phone (or Call)
2. Storage → Clear Cache (NOT Clear Data)
3. Force Stop
4. Restart your phone
5. Try Settings again, or just use codes

 

To be frank: The Settings screen interface for call forwarding is unreliable. I’ve wasted so much time watching that spinning wheel. Now I just use codes directly. It’s faster and more reliable.

Codes work even when the graphical interface is broken.

 

Problem #7: The Carrier Service Isn’t Enabled on Your Account

This is rare but when it happens, nothing else will fix it.

What’s Happening
❯

Call forwarding is a carrier feature. Some accounts don’t have it enabled by default—especially new SIM cards or special prepaid plans.

 

How to Check
❯

Dial *#21# and press call.

If you get:

• “Voice call forwarding: Not forwarded” → Feature works, just not active
• “Unable to access network” or “Service not available” → Feature not enabled

🔧 The Fix: Call your carrier and specifically ask: “Is call forwarding enabled on my account?”

🗣️ What to Say: “Hi, I’m trying to activate call forwarding but getting [your error message]. Can you verify if call forwarding service is enabled on my line? My number is [your number].”

 

Carrier Numbers:

• MTN: 180
• Airtel: 111
• Glo: 121
• 9mobile: 200

They might need to activate it from their end. Takes 2-5 minutes usually.

Business Lines: Some MTN business plans have call forwarding as an optional paid add-on. If you’re on a corporate plan, ask specifically about this.

 

When Nothing Works: The Nuclear Options

Tried everything above and still broken? Here’s what’s left.

 

Nuclear Option #1: Try a Different Network

If you have a dual-SIM phone, try your forwarding destination on the OTHER SIM. Sometimes there’s weird network routing issues between carriers.

And if you just want to turn this whole thing off and start fresh, here’s the complete guide to canceling call forwarding.

 

Nuclear Option #2: Factory Reset Your Phone

I really, really don’t recommend this unless you’re desperate. But if your phone has some deep software corruption, this will fix it.

Backup everything first. You’ll lose all data.

 

Nuclear Option #3: Get a New SIM Card

If your SIM is old (3+ years) or damaged, it might have issues with modern network features. Visit your carrier’s office, get a new SIM with the same number. Free on most networks.

 

Nuclear Option #4: Accept That Call Forwarding Is Broken

Real talk? Call forwarding via USSD codes is 20-year-old technology that carriers barely maintain anymore.

If you’re using this for business or anything important, you need a modern solution.

 

Why I Stopped Fighting With Call Forwarding

After the 100th time (I may be exaggerating a bit) troubleshooting forwarding issues—for myself, for clients, for family members—I gave up.

Know what I did? Got a PressOne virtual number.

Why? Because:

• Forwarding settings in an app (no memorizing codes)
• Works over internet (doesn’t need cellular signal)
• Can change routing in 5 seconds from my phone
• Never got a “CONNECTION PROBLEM” error
• Set up business hours, backup numbers, all that
• Costs less than I was spending on forwarding charges

 

I’m biased. But after spending literally hours of my life fighting with ##002# and *#21# and all that garbage, I’m just saying—there’s an easier way.

If you’re setting up forwarding more than once a month, or if it’s for business, just “get a proper virtual number →. Save yourself the headache.

 

Quick Reference: All the Fixes

Problem #1: Wrong Number Format → Use 11 digits starting with 0 (08012345678)

Problem #2: Bad Signal → Move to better location, toggle Airplane Mode

Problem #3: Do Not Disturb / Call Barring → Turn off DND, dial #33# to check barring

Problem #4: Wrong Code → ##002# to reset, use correct code (*21 vs *61)

Problem #5: CONNECTION PROBLEM Error → Reset network settings, Airplane Mode, remove SIM

Problem #6: Spinning Wheel → Force close app, restart phone, use codes instead

Problem #7: Service Not Enabled → Call carrier (180/111/121/200), ask them to activate it

 

Actually Check This Right Now

Before you close this tab, do me a favor.

Dial *#21# and press call.

Look at the screen. Is call forwarding active when you didn’t mean it to be?

Because that happens more than you’d think, and you might be missing calls without knowing.

If you see a number you don’t recognize, dial ##002# right now.

Someone might have activated forwarding on your line without you knowing. (Yeah, it’s a security risk. That’s why you should check.)