Calling option

To use two different carriers, your iPhone must be unlocked. Otherwise, both plans must be from the same carrier. If a CDMA carrier provides your first SIM, your second SIM won't support CDMA. Contact your carrier for more information. 

If you have an enterprise or corporate cellular service plan, check with your company administrator to see if they support this feature.

Use two phone numbers for calls, messages, and data

Now that your iPhone is set up with two phone numbers, here's how to use them. 

Let your iPhone remember which number to use

When you call one of your contacts, you don't need to choose which number to use every time. By default, your iPhone uses the same number that you used the last time you called that contact. If you haven't called that contact, your iPhone uses your default number. If you want to, you can specify which number to use for your calls with a contact. Follow these steps:

1. Tap the contact.
2. Tap Preferred Cellular Plan.
3. Tap the number you want to use with that contact.

Make and receive calls

You can make and receive phone calls with either phone number.

With iOS 13 and later, when you're on a call, if the carrier for your other phone number supports Wi-Fi calling, you can answer incoming calls on your other number. When you're on a call using a line that isn't your designated line for cellular data, you need to turn on Allow Cellular Data Switching to receive calls from your other line. If you ignore the call and you have voicemail set up with your carrier, you’ll get a missed-call notification and the call will go to voicemail. Check with your carrier for Wi-Fi calling availability, and find out if additional fees or data usage applies from your data provider.

If you're on a call and your other line shows No Service, either your carrier doesn't support Wi-Fi calling or you don't have Wi-Fi calling turned on.1 It could also mean Allow Cellular Data Switching is not turned on. When you're on a call, an incoming call on your other phone number will go to voicemail if you set up voicemail with your carrier.2 However, you won't get a missed-call notification from your secondary number. Call Waiting works for incoming calls on the same phone number. To avoid missing an important call, you can turn on call forwarding and forward all calls from one number to the other. Check with your carrier for availability and to find out if additional fees apply.

1. Or if you're using iOS 12. Update to iOS 13 or later to receive calls when you're using your other number.

2. If data roaming is on for the number that uses cellular data, then Visual Voicemail and MMS will be disabled on your voice-only number.

Switch phone numbers for a call

You can switch phone numbers before you make a call. If you're calling someone in your Favorites list, follow these steps:

1. Tap the Info button .
2. Tap the current phone number. 
3. Tap your other number. 

If you're using the keypad, follow these steps:

1. Enter the phone number.
2. Tap the phone number, near the top of the screen. 
3. Tap the number you want to use.