Threema calls don’t work properly if there are certain kinds of network restrictions.
- If you use security measures like a firewall, antivirus software, an ad blocker, or a VPN , please make sure that Threema is excluded from their activities.
- Make sure that you are not connected to the guest profile of the local Wi-Fi router; many routers do not allow certain connections for guests.
- If you have only tried one network, please try to make a call using a different network (e.g., mobile data).
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If the problem only occurs when calling specific contacts, please check their verification level. When calling contacts with the verification level 1 (red), calls are routed
through the Threema server to disguise the IP addresses. In rare cases, this may lead to connectivity issues. Therefore, increase the verification level by scanning the contact’s
QR code or using the contact synchronization.
- If you use one or both of the following options, please deactivate them to try if that resolves the issue:
- “Threema > Settings > Secure calls (Android) or Threema Calls (iOS) > Always relay calls”
- “Threema > Settings > About Threema > Advanced options > IPv6 for calls and web” (Android) or “Threema > Settings > Advanced > IPv6” (iOS).
