Whether you’re making a call you’d rather keep anonymous or just value your privacy, Cell C private number code supports the standard GSM caller ID blocking codes used across South African networks. Here’s exactly how to use them, including how to reverse it if you’ve hidden your number by accident.
How To Hide Your Number For a Single Call
Dial #31# immediately followed by the full number you want to call, then press the call button. For example, to call 084 123 4567 privately, dial:
#31#0841234567
The recipient will see “Private Number,” “Unknown,” “Withheld,” or a similar label instead of your actual number, depending on their phone’s caller ID display settings. This method only affects that one specific call — your number will show normally again on your next call unless you repeat the code.
How To Show Your Number If You’ve Set It To Hidden By Default
If your line is set to hide your number on every call by default (either because you requested this from Cell C, or accidentally activated it), you can override it for a single call by dialling:
*31# followed by the recipient’s number
This is the reverse of #31# — it forces your number to display for just that one call, even if your default setting is to stay hidden.
Making It Permanent
The temporary codes above only apply per call. If you want your number permanently hidden on every outgoing call, you have two options:
- Contact Cell C customer care on 135 (free, Cell C number) or 084 135 (other networks) and request permanent Caller ID blocking on your line
- Check your phone’s own settings — most smartphones have a caller ID toggle under Settings > Phone/Calls > Additional Settings > Caller ID (Android) or Settings > Phone > Show My Caller ID (iPhone). Note that this is a device-level setting, and some phones require network support for it to actually take effect, so combining it with the network-level request to Cell C is the most reliable approach.
Why Your Number Might Show As Private Even When You Didn’t Hide It
If people keep telling you your calls come through as “Private” or “Unknown” and you’re sure you didn’t activate this, a few things could explain it:
- An accidental *31# or #31# dial — easy to trigger by mistake if you’ve tapped a saved contact with a prefix code attached, or copy-pasted a number that had a code included
- A previous permanent block that was never removed — if you or someone else requested permanent blocking in the past and forgot to undo it
- A phone settings change during a software update — occasionally resets or alters caller ID preferences
- A second-hand or refurbished phone with leftover settings — if you bought your device used, a previous owner’s caller ID preference can sometimes persist until you actively change it yourself
To fix this, dial *31# on its own (without following it with a number) in some regions, though the more reliable fix is to call Cell C customer care directly and ask them to confirm and reset your caller ID setting from their side.
Does This Code Work The Same On Other Networks?
Yes — unlike many USSD shortcuts, which are network-specific, #31# and *31# are part of the international GSM standard for Calling Line Identification Restriction (CLIR), not a Cell C-specific code. This means the exact same codes work identically on Vodacom, MTN, and Telkom in South Africa, and in most countries worldwide. If you’re used to hiding your number on a different network, you don’t need to relearn anything when switching to or from Cell C — this is one of the few genuinely universal codes across the entire industry.
Setting Caller ID Preferences On Your Phone Directly
Beyond the network codes, most phones let you manage this from settings directly, which can be more convenient if you frequently switch between hiding and showing your number:
On Android (varies slightly by manufacturer):
- Open the Phone app
- Tap the three-dot menu or Settings icon
- Look for “Calls” or “Call Settings”
- Find “Additional Settings” or “Supplementary Services”
- Tap “Caller ID” and choose Hide Number, Show Number, or Network Default
On iPhone:
- Open Settings
- Scroll to Phone
- Tap “Show My Caller ID”
- Toggle it on or off
Keep in mind that on iPhone specifically, this toggle only works if Cell C’s network supports the underlying feature — if the toggle doesn’t seem to have any effect, the network-level code (#31#) is the more reliable fallback, since it operates at the network level rather than depending on your specific device’s software implementation.
A Privacy Note Under South African Law
South Africa’s Protection of Personal Information Act (POPIA) governs how your personal information, including your phone number, can be collected and used by businesses — but it doesn’t directly regulate caller ID display between individuals making personal calls. Caller ID blocking is a feature of the mobile network itself (a GSM/CLIR standard), not a POPIA-governed data process. If your specific concern is a business misusing your number after you’ve called them, that’s a POPIA matter you’d raise directly with that business or, if unresolved, the Information Regulator — separate from the caller ID blocking covered in this guide.
Legal and Practical Considerations
A few things worth knowing before you rely on caller ID blocking:
- Emergency numbers ignore CLIR — if you call 10111 (police) or 10177 (ambulance), your number will always be visible to emergency services regardless of any private number setting, for safety reasons
- Some businesses and call centres won’t answer private numbers — many companies configure their systems to automatically reject or screen calls that don’t display a number, so if you’re trying to reach a business, consider showing your number for that specific call
- It’s not a substitute for genuine privacy protection — caller ID blocking hides your number from casual display, but your identity remains fully known to Cell C and is available to law enforcement through the proper legal process if required for an investigation
Frequently Asked Questions
Does hiding my number cost anything?
No, both #31# (hide) and *31# (show) are free standard network codes.
Will this work if I’m calling from WhatsApp or another calling app instead of a normal call?
No — these codes only apply to regular cellular voice calls through your phone’s dialler. App-based calls (WhatsApp, Facebook Messenger, etc.) use their own separate privacy settings.
I dialled #31# by mistake and now my number is always hidden — how do I fix this?
This shouldn’t happen from a single #31# dial, since it’s a per-call code, not a permanent setting. If your number is consistently showing as hidden, it’s more likely a permanent block was set previously — contact Cell C customer care on 135 to check and reset your setting.
Can the person I called still find out my number some other way?
Not through their phone directly, no. However, if you’re calling a company with caller verification systems (like a bank), they may still identify you through other account verification steps unrelated to caller ID.
Does this work for SMS too?
No — caller ID blocking only applies to voice calls. Your number is always visible to the recipient on a standard SMS, regardless of any caller ID settings.
Can I hide my number when calling an international number?
Generally yes, since CLIR is an international GSM standard, but success can depend on the receiving country’s network and whether it honours CLIR requests from foreign networks. If it’s important for a specific international call, test it on a lower-stakes call first if possible.
If I hide my number, can the person still call me back?
No — since your number wasn’t displayed to them, they have no way to call you back unless they already had your number saved from a previous contact, or you tell them directly during the call.
Explore More
- Want the full list of Cell C shortcuts? See our complete Cell C USSD codes guide
- Need to reach someone with no airtime? See our Cell C Please Call Me guide
