On an iPhone, dialing *67 before a number temporarily hides your caller ID for that single call, signaling the network to send a "withheld" line instead of your number. This behavior is rooted in SS7/TDM interoffice signaling, so it works reliably on cellular networks and most landline routes, though some carriers, VoIP services, or premium numbers may reject or override the block. Below you will find definitions, settings, limitations, and carrier-specific notes to help you understand when *67 actually works on iPhone and what to expect in different scenarios.
What *67 Does on iPhone Calls
*67 is a vertical service code (VSC) that requests caller ID blocking for a single outgoing call without changing your device or account settings. It is not an iPhone-specific feature; it is a network instruction that tells the switch to withhold your number from the recipient’s caller ID. The change is signaling-only on a per-call basis, so it does not modify your phone’s software or your line’s permanent privacy settings. This makes *67 a quick, on-demand option if you want to avoid displaying your number to one recipient while keeping it visible for other calls.
How *67 Works Under the Hood
When you dial *67, your iPhone sends the digit sequence to the cellular network before connecting the call. The network then places the caller ID restriction flag in the call setup signaling (typically ISDN PRI or SS7 messages) so that the destination switch does not send your number. In practice, this results in the recipient seeing "Private," "Unknown," "Withheld," or a similar label instead of your phone number. Because the restriction is applied by the switch, *67 works even if your phone shows Caller ID disabled in Settings; it relies on network behavior more than phone settings.
Limitations and Edge Cases
Although *67 is widely supported, it is not universally honored. Some carriers, especially with VoIP or mobile virtual network operators (MVNOs), may ignore the code or require an alternate blocking method. Certain call types, such as 800/888/877 freephone numbers, toll-free verification lines, or premium-rate services, may not accept withheld caller ID and could block the call. Additionally, international calls involve multiple roaming agreements, and local number portability or interconnected VoIP rules can affect whether the code propagates correctly. Below is a concise reference table summarizing key attributes and source-backed details.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Mechanism | Per-call network signaling (SS7/ISDN) to withhold caller ID | Carrier and IETF specifications |
| Calling Formats | *67 + number (no pauses; dial *67 then the full number) | Carrier customer guidance |
| Device Scope | Network-level block, not stored in iPhone settings or SIM | Technical specifications |
| Toll-Free Lines | Often reject withheld IDs; may fail to connect | Carrier policy documentation |
| International Use | Variable support; depends on roaming agreements and local regulation | Regulatory and carrier notices |
| Permanent vs Temporary | *67 is temporary (per call); does not change account or SIM settings | Carrier FAQs |
iPhone Settings That Affect Caller ID
iOS includes several places where caller ID behavior can be configured, and understanding these helps you avoid confusion when *67 or other methods are used. The settings do not change how *67 signals the network, but they determine which number or method appears if your carrier does not accept a withheld request or if you make calls over VoIP. Reviewing these options ensures you know which mechanism will apply in a given scenario.
Show My Caller ID Toggle
Go to Settings > Phone > Show My Caller ID. When this toggle is on, your iPhone allows your number to be sent with calls, subject to carrier handling. When it is off, your device may send a default restriction depending on account settings or network behavior. On many carriers, turning this off results in your number being blocked for all calls, but outcomes vary, especially with VoIP or international dialing. *67 overrides this toggle for a single call by explicitly requesting a withheld ID at the network level.
Call Forwarding and Conditional Call Forwarding
If call forwarding is active, the forwarded call may originate from a different switch or number, which can alter how caller ID is presented. Conditional forwarding, such as forwarding when busy or no answer, may further complicate tracing. In these cases, *67 may still block the originating leg, but the forwarded termination point could display a different line or an automated ID depending on the provider. If call behavior seems inconsistent, first verify that call forwarding is either disabled or intentionally configured.
Carrier Settings and Updates
Carrier settings on iPhone influence how dial codes like *67 are processed, especially for calls that traverse LTE, 5G, or VoIP infrastructures. Carriers occasionally push updates that modify privacy, authentication, or number presentation rules. After an update, behaviors can change for *67, particularly if the carrier adjusts how it handles withheld ID requests or toll-free interconnects. When troubleshooting *67, ensure your carrier settings are up to date by installing any prompted updates and checking the carrier’s official guidance for calling features.
Practical Alternatives to *67 on iPhone
If *67 does not produce the desired result, or if you need more reliable per-call blocking, consider these alternatives. Each method pairs a different technical mechanism with varying scope, from per-call codes to account-level settings.
- Dial *67 before each number for temporary, per-call blocking on cellular and most landline routes.
- Use your carrier’s web portal or app to set default caller ID blocking, which applies to all outbound calls until changed.
- Contact your carrier to permanently block caller ID on your line, which removes your number from all outbound calls unless explicitly unblocked.
- For calls over Wi‑Fi or VoIP, check whether your carrier or third‑party app offers in-call settings or account toggles for number presentation.
- On business lines or with enterprise services, consult your telephony provider about privacy classes and line-level restrictions that may be more appropriate than per-call codes.
Carrier and Regulatory Variations
Telecom regulation and interconnection rules differ by country, and these differences influence whether *67 is honored, especially on international routes. Regulators may require carriers to provide number identification for billing, emergency services, or fraud prevention, which can limit how aggressively a caller ID block can be applied. Similarly, wholesale agreements and number portability databases can affect how a call is routed and whether the withhold flag is preserved. If you travel internationally or use a VoIP service that routes over internet endpoints, verify with your provider how *67 is handled in the specific countries you contact.
When *67 Might Not Work as Expected
Even when *67 is technically functional, real-world outcomes can vary. A recipient using a third-party call management app, a carrier that normalizes unknown lines, or a business that rejects private calls may still see some form of identification or a blocked call. In other cases, *67 may cause the call to land in spam or unknown queues, particularly with toll-free or high-risk number ranges. If your goal is reliable privacy, combine *67 with account-level settings and confirm block behavior on a test call before relying on it for sensitive contacts.
Summary and Best Practices
*67 can hide your number on a per-call basis by prompting the network to present your call as withheld, and it generally works on iPhone across cellular and most PSTN routes. However, success is not guaranteed for toll-free, international, or VoIP call paths, and outcomes can depend on carrier policies and recipient equipment. Use *67 for occasional, one-off calls, and complement it with carrier account settings or device toggles for more consistent control. Verify behavior with a test call when privacy is critical, and check with your carrier if you regularly reach numbers that fail to accept withheld IDs.