WeChat treats phone contacts as “leads.” You have to manually “add” them even after the app finds them in your address book.

• Step 1 (Linking Your Number): For contact syncing to work, you must link your own mobile number to your WeChat account (Me > Settings > Account Security > Phone).

• Step 2 (Uploading Contacts): 1. Go to the Contacts tab. 2. Tap New Friends. 3. Tap Mobile Contacts (or “Add Mobile Contacts”). 4. WeChat will show you a list of people in your phone book who use WeChat. You must tap Add next to each one to send them a friend request.

Wiper (known for its “wipe” or delete feature) follows the standard “mirroring” protocol but focuses heavily on privacy.

• Step 1 (Permissions): Ensure Contacts access is enabled in your iPhone or Android system settings.

• Step 2 (The Contact List): 1. Open Wiper and go to your Contacts or New Message screen. 2. Wiper usually automatically scans your address book. 3. If they don’t appear, look for an Invite Friends or Sync option within the settings.

• Note: Wiper has gone through several updates and ownership changes; if the sync feels sluggish, it often helps to ensure the phone numbers in your address book include the plus (+) sign and country code.

LINE is widely used in Asia and requires an “Auto-Add” toggle to bridge your address book to the app.

• iPhone: Settings > Privacy & Security > Contacts > Toggle LINE to ON.

• Android: Settings > Apps > LINE > Permissions > Contacts > Allow.

• Inside LINE: Home tab > Settings (gear icon) > Friends > Toggle Auto-add friends to ON. Use the circular arrow icon next to “Last Updated” to force a refresh.

Signal is highly privacy-focused and will ask for permission when you try to start your very first chat.

• iPhone: Settings > Signal > Toggle Contacts to ON.

• Android: Settings > Apps > Signal > Permissions > Contacts > Allow.

• Inside Signal: Tap the Compose icon (pencil). If your contacts don’t appear, pull down on the list to refresh. Signal will only show people from your contacts who also have Signal installed.

On iPhone:

• Go to Settings > Privacy & Security > Contacts.

• Find WhatsApp in the list and toggle the switch to On.

• Alternatively: Go to Settings > scroll down to WhatsApp > toggle Contacts on.

On Android:

• Go to Settings > Apps (or App Management).

• Select WhatsApp > Permissions.

• Tap Contacts and select Allow.

Telegram uses a cloud-sync method, meaning once you sync your contacts, they are available on the desktop app as well.

• iPhone: Settings > Telegram > Toggle Contacts to ON.

• Android: Settings > Apps > Telegram > Permissions > Contacts > Allow.

• Inside Telegram: Settings > Privacy and Security > Scroll down to Data Settings > Toggle Sync Contacts to ON.

Zalo is the primary messenger for Vietnam and follows a similar “Sync” structure.

• iPhone: Settings > Zalo > Toggle Contacts to ON.

• Android: Settings > Apps > Zalo > Permissions > Contacts > Allow.

• Inside Zalo: Tap the Contacts tab at the bottom > Tap the Update icon (usually at the top of the contact list) to pull in new phone numbers from your address book.

KakaoTalk is quite proactive about syncing, but it has a specific setting to “Auto-Add” people who are in your phone’s contacts.

• Step 1 (Permissions): Just like WhatsApp, ensure your phone settings (iOS or Android) have allowed KakaoTalk to access your Contacts.

• Step 2 (In-App Sync): 1. Open KakaoTalk and tap the Settings (gear icon) in the top right. 2. Tap General Settings > Friends. 3. Toggle on Auto-Add Friends. This will automatically add anyone in your phone contacts who is also a KakaoTalk user to your friend list.

• Manual Refresh: In that same Friends menu, you can tap the refresh icon next to “Last Updated” to force a sync immediately.