frogtalk.xyz/i/<name>
will land on a join page.
If these four emoji match the ones shown on your friend's device, your messages are end-to-end encrypted and nobody else can read them.
Derived from both nicknames · Server only sees ciphertext.
Verify this number with your contact in person or over a trusted channel. If both sides see the same 60 digits, your call is end-to-end secure and no signalling server can MITM it. A number that changes between calls means the peer's identity key rotated (re-install — or tampering).