Are you talking about Delta Chat? It used to use Jitsi (and similar services) but not in an integrated way, i.e. it would simply generate links to a Jitsi web instance. See What happened to Video Chat?.
Are you talking about Delta Chat? It used to use Jitsi (and similar services) but not in an integrated way, i.e. it would simply generate links to a Jitsi web instance. See What happened to Video Chat?.