Tact-VC tries all of these ways at once and uses whichever works:
- IPv6. Most home connections have it. Both apps send to each other at the same time, which opens both routers' firewalls. No setup needed.
- A port on your router, opened automatically or forwarded by hand. This makes you reachable over IPv4. See Automatic port opening.
- IPv4 hole punching. Works in most cases when at least one side is reachable.
- Introductions by friends you both have or a Vide, after your addresses changed. They only pass on addresses; the call still goes directly. See What is a Vide?.
A call fails only when neither side has working IPv6 and neither is reachable over IPv4. This typically happens when both sit behind shared addresses, see Shared internet address.
Network values
| Setting | Value |
|---|---|
| Protocol | UDP |
| Port | 47100 (Settings → Network → UDP port) |
| Bandwidth | about 100 kbit/s up and down per other person in the call |
| Router features used | UPnP-IGD or NAT-PMP, if allowed |