Question about myStrom Switch Zero

Hello everyone I bought two from Swisscom directly and where I still had a Swisscom plan, everything worked fine. Now I have a new supplier and nothing works anymore :(. Can it really be that these only work directly via the Swisscom network and are all myStrom products only possible via Swisscom or does the Switch Zero also work via the Sunrise network, for example? Thank you for your help.