Question about Yealink T48g

As far as I know, the operation of IP telephones (foreign telephones) is only possible with the latest Internet Box Standard.
To do this, you must assign a fixed IP to the telephone and switch to expert mode on the Internet Box and click on the button Add new access data under the heading Telephone local IP access data. Then select the fixed IP on the telephone, assign call numbers and select any user name and password. (These must be used on the telephone afterwards).

Thank you very much for your answer. I have now bought a phone anyway. It was child's play to register the device with the new Swisscombox. The name display works perfectly. (I didn't have to set anything up for this).
The only disadvantage is that after a power failure the device starts too quickly and the modem is not yet ready. This means that the phone no longer logs on automatically. Solution: Restart the phone again as soon as the modem is ready.
Conclusion: One of the best phones I have had in this price range.

The phone does not offer an interface for this, possibly only with a lot of tinkering. I recommend a phone from the Gigaset series, they all offer this function.