All the GSM codes you need, sorted by category. Search or copy with a single click to configure your phone forwarding, blocking, or caller ID settings.
What are GSM codes?
GSM codes (also called USSD codes or MMI codes) are short dial sequences that you enter into your phone's dialer to activate, deactivate, or check features of your mobile network provider. They work on virtually any mobile phone and with any provider worldwide, without an app or internet connection.
They are most commonly used for call forwarding, but GSM codes also control call waiting, caller ID, call barring, and device information such as the IMEI number.
How to use GSM codes
- Open the Phone app (the app you use to make phone calls).
- Enter the code exactly as shown, including all asterisks (*) and hashes (#).
- Replace placeholders like [phone] with the actual phone number (including country code).
- Press the call button.
- Wait for confirmation on the screen.
Codes beginning with * or ** activate a function. Codes beginning with # or ## deactivate it. Codes beginning with *# check the current status.
Detailed call forwarding instructions
If you specifically want to set up call forwarding, use our call forwarding helper tool. It lets you select your provider and generates the exact code using your phone number.
Forward missed calls to an AI assistant
The most practical use of call forwarding codes: redirecting unanswered calls to a service that will actually answer. Hallodesk is an AI-powered phone assistant that picks up when you're unavailable, asks the caller about their reason for calling, and sends you a summary. Setup with the forwarding codes takes about 2 minutes.
