You can add contacts to the Facebook Messenger application by using your phone's contact list, entering a specific phone number, or scanning the code for adding another Facebook Messenger user. Adding a contact is possible on the versions of Facebook Messenger for iPhone and for Android.
Steps
Method 1 of 3: Add phone contacts

Step 1. Open Facebook Messenger
Tap the Messenger app icon that looks like a lightning bolt on a chat bubble.
If prompted, enter your phone number and Facebook password to log in before continuing

Step 2. Go to the Home tab
It's the house icon at the bottom left of the screen.

Step 3. Tap the profile icon
You will find it, either at the top left (on iPhone) or at the top right (on Android).

Step 4. Select Contacts
This option is at the bottom middle of the page.

Step 5. Sync your phone contacts
If Contacts sync is turned off, you will see a white switch (on iPhone) or the word "No" under the Sync option (on Android). Press the switch or To sychronize to activate contact synchronization. This will add all Messenger users in your contact list to the Messenger application.
- If you see a green switch (on iPhone) or the word “Yes” under Synchronize, it means that your phone contacts are already synchronized with Messenger.
- If you are using an iPhone, you may need to allow Messenger to access your contacts first. For that open Settings, scroll the page, press Messenger then slide the white switch Contacts to activate synchronization.
Method 2 of 3: Add a phone number

Step 1. Open Facebook Messenger
The Messenger app icon looks like a lightning bolt on a chat bubble.
If necessary, enter your Facebook phone number and password to log in before continuing

Step 2. Tap the contacts tab
These are horizontal lines stacked in the lower left corner of the screen (on iPhone) or at the top right (on Android).

Step 3. Select +
This option is at the top right of the screen (if you are using an iPhone) or at the bottom right (if you are using an Android). Tap on it to open a menu.

Step 4. Press Enter Phone Number
The option Enter a phone number is in the menu. Tap it to open a text field where you can enter a phone number.
If you are using an Android, skip this step

Step 5. Enter a phone number
Tap the text field and then use the onscreen keyboard to type a phone number.

Step 6. Tap Save
This option is located at the top right of the window. Tap it to search Facebook for a person whose name matches the phone number.
- On Android, you will just have to press Add a contact and skip the next step.

Step 7. Add the person
Tap the option Add to send a friend request to the person corresponding to the phone number you entered. If she accepts your request, you will be able to chat with her on Facebook Messenger.
- You can also send a message to that person, however they will need to accept the invitation to be able to view it.
- If the number you typed does not match a Facebook profile, you can press Invite on Messenger to send an invitation to the person.
Method 3 of 3: Scan a code

Step 1. Open Facebook Messenger
To open Facebook Messenger, tap the lightning bolt icon on a chat bubble
If prompted, enter your phone number and Facebook password to log in before proceeding further

Step 2. Go to the Contacts tab
The Contacts tab icon looks like a stack of horizontal lines at the bottom left of the screen.

Step 3. Tap Scan Code
If you're using an Android, you'll need to tap Scan Messenger Passcode instead. This option is at the top of the screen. It opens a code scanner.

Step 4. Have a friend extract their code
For this, he only needs to open the Contacts tab, press Scan the code then select My code at the top of the screen.

Step 5. Point your camera at the code
The code should be centered in a circle on your phone screen.

Step 6. Press ADD TO MESSENGER
You will see this option at the top of the screen. Tap it to add the person to your Messenger contacts.
Advice
- By default, your Messenger contact list is made up of your Facebook friends. You can add friends on Facebook to automatically add these people to your Messenger list.
- If you add a contact who does not add you back, you can say hello by tapping the option Hello to notify him without sending him a message that you want to discuss.