Tips and settings to know if you use two SIM lines on iPhone

Go through these tips and settings to make the most of the two SIM lines on your iPhone and ensure you have the best data and voice call experience.

All recent iPhone models support setting up multiple SIM cards. I have set two on mine: one main number for all calls and data, and the other a secret number I use only for my bank accounts and occasionally for backup cellular data.

I know people who use two lines – one for personal calls and the other for business calls. Then, there are frequent travelers with multiple eSIMs on their iPhone for different countries they visit.

If you have set up more than one SIM, use these tips to improve your user experience.

Manage and customize mobile settings for both SIM lines

First off, here’s how you can access your cellular settings to manage multiple SIM lines.

1. Open the Settings app on your iPhone.
2. Tap Cellular, Mobile Service, or Mobile Data.
3. You’ll see a ‘SIMs’ heading if you have two or more lines set up on your iPhone. Tap one to select it.
4. You can now manage various settings related to it. For instance, I have set low data mode on my second SIM, which has a limited plan, but my main SIM is set to ‘Allow More Data on 5G,’ so its unlimited data plan can be used freely for iCloud Photos, device backups, and other data-hungry tasks.

Set up different names for each line

Having distinct names for each SIM card lets you differentiate between them and use each as needed. As an example, my brother has two SIM cards from the same carrier. Now, one of the lines (provided by his office) has unlimited internet, while the personal one is on a limited plan. Having different line names ensures he uses the right one for data and calls.

Follow these steps to change the SIM line name:

1. Go to SIM settings (iOS Settings > Cellular > select a SIM line).
2. Tap Cellular Plan Label.
3. Select a suggested name like Business or Personal, or add a custom label. Remember that the first letter of the label (like B for Business) is shown as an icon when the full name isn’t displayed. Therefore, if you’re planning on using the custom names for your different labels, ensure they don’t start with the same alphabet.

Set different ringtones for both lines

iOS lets you set different ringtones for your SIM lines. This way, you can immediately identify if an incoming call is on your personal or business line (or whatever identifier you use).

1. Go to iPhone Settings > Sounds & Haptics > Ringtone.
2. Select a SIM line and then pick the desired tone.

Set up a default line for voice calls

Setting a default SIM line for calls ensures that when you call a person from your contacts list, tap a number on a webpage or another app, or call after typing the number on the keypad, the call will always use your default SIM card.

Of course, you can choose another SIM on a per-case basis, and any custom preferences are honored (explained below).

Here’s how to assign a default SIM for calls:

1. Open iPhone Settings and tap Cellular.
2. Tap Default Voice Line.
3. Select your preferred line for cellular voice calls.

Set up a default line for voice calls and messages for a specific contact

Imagine you have set your AT&T line or your personal line as the default for all calls, but you want to always use your Verizon office line to call and text a specific office colleague. In this case, you can assign a preferred SIM line for this person, which will override your default voice line settings.

1. Open the Phone or Contacts app on your iPhone.
2. Find the person’s saved contact and tap it.
3. Tap the tiny Default sim line or Last Used text, as shown in the screenshot below, choose another, and tap the checkmark icon. Now, your iPhone will always use this non-default SIM line when calling this person.

Select another line for returning a call or making a new one

Favorites or recent calls

1. Tap the info icon ⓘ next to their name if you’re using the classic layout. Otherwise, go to their contact page.
2. Tap the Default or Last Used label to change it.
3. Then, tap the phone call icon to make a call with the newly selected line.

Using keypad

1. Enter the phone number.
2. Tap the SIM label icon in the top-left corner and select another line.
3. Finally, tap the green call button.

Block calls on one of the SIM lines when you sleep or work

Let’s say you use your personal and business lines on your iPhone. And at night, you don’t want to entertain calls on the business SIM phone number. You can use the Focus filters feature to select the SIM whose incoming calls will be allowed to you as long as Sleep Focus is active. Of course, this also works for other Focus modes, such as Do Not Disturb, Work, and Gaming.

Use both numbers for FaceTime and iMessage

Go to iPhone Settings > Apps > FaceTime or Messages to set these up with your second SIM line.

Set up both SIM lines on your Apple Watch

Just like iPhone, you can add more than one SIM line to your cellular Apple Watch, provided both your cellular carriers and plans support it.

About Call Waiting when using two SIM lines

When you’re on a call on your personal number, and someone calls you on that same number, then the Call Waiting feature will alert you to the incoming call. However, Call Waiting doesn’t alert you if you’re on a call on your personal number, and someone calls on your business number.

If knowing who is calling you on the other line is important, you can set up call forwarding on the business number to have its calls forwarded to your personal number. After that, even when you’re on a phone call on your personal number, and someone calls you on your business number, the Call Waiting feature will alert you to it.

Set up a default line for cellular data

At any given time, you can only use one SIM line for cellular data. Go to Settings > Cellular > Cellular Data and select your preferred line. You can also do this by expanding the network tile in iOS Control Center.

Use cellular data when on phone calls

If your carrier uses the latest advanced technology, such as VoLTE (Voice over LTE (4G voice calls)) or VoNR (Voice over New Radio (5G voice calls)), then you can use cellular data even when you’re on a phone call. No extra setup is required.

However, if you notice that you can’t use cellular data when on a phone call, go to Settings > Cellular > Cellular Data and turn on Allow Cellular Data Switching. This will allow your iPhone to use cellular data from the other SIM line (like your personal line) when you’re on a call on your different line.

Switch to another number during a message conversation

You can send SMS, MMS, or RCS text using your second line without starting a new conversation.

1. Open the Messages app and go to a conversation.
2. Tap the person’s name or number at the top.
3. Tap Conversation Line and choose another.
4. Return to the conversation screen and send a new text. It will go from the SIM line you selected in the previous step.

Sort messages based on SIM line

The iOS Messages app lets you see texts filtered by SIM line. This way, you can view all messages received on your personal or business number without having to scroll through the chats list and focusing on the tiny SIM label icon.

1. Open the Messages app on your iPhone.
2. Tap the three-line icon at the top.
3. Select a SIM under the ‘Filter By’ heading. Repeat step 2 and tap Messages to view a unified inbox.

View cellular data usage for each line

Go to Settings > Cellular > Cellular Data and select a line. Then, return to the main cellular settings screen to see the usage.

Note that if you turn off cellular data for an app, it remains off for all your SIM lines. Having the option to manage this on a per-SIM basis would be a nice addition in future iOS updates.

Turn off a SIM line to save battery

Whenever I travel, I turn off one of my SIM lines to save battery (iPhone having to connect to two towers consumes more battery). But before I do that, I usually set up call forwarding from the second number to my main number so I don’t miss any important phone calls.

To turn off a SIM line:

1. Go to iPhone Settings > Cellular and select a SIM line.
2. Toggle off the switch next to ‘Turn On This Line.’

Also, check out: 15 new features added to the iPhone Phone app