It works with Sunrise (phone, internet, TV): this device is supported. But:
Before to buy it: phone Sunrise, and ask if they still support this device: things changes, and this router is becoming old. They gives this exact device to Sunrise Business clients, so they support the device (as end 2019), but they cannot deliver it to private clients.
You will receive also the Sagem box (which I never unboxed).
I think they should do some configuration, in order to use this device: for the initial few hours, internet packets were lost inside Sunrise routers, but after them, the router was fully working. On my configuration: with old FB (ADSL, from Sunrise) and new FB (5490 from Digitec) I have "Other provider" (so none of Sunrise), and VLAN seems different. But sunrise set it up for me. [I copied all configuration from old router to new + just tell that you have internet from fiber]. Note: expert view, allow ISP to configure/change configuration of the modem.
I'm happy with this modem (on Sunrise). Note: I have two additional "mesh" FB 7490 routers (also from Digitec), two Sunrise TV boxes, Devolo, etc.: Only with FritzBox you can have a otherwise complex setup very simple.