Yes, Swisscom will switch off the 2G/GSM mobile network throughout Switzerland by the end of 2020 at the latest:
[https://www.swisscom.ch/de/about/medien/press-releases/2015/10/20151008-MM-Swisscom-ruestet-ihr-Mobilfunknetz-fuer-die-Zukunft.html] (https://www.swisscom.ch/de/about/medien/press-releases/2015/10/20151008-MM-Swisscom-ruestet-ihr-Mobilfunknetz-fuer-die-Zukunft.html)
In January 2021, voice telephony via the 3G/UMTS mobile network will most likely still be possible. The 3G/UMTS mobile network is expected to be switched off at some point after 2021. Voice telephony via the 4G/LTE mobile network does not seem to me to be sophisticated enough and is struggling with various teething problems.
Swisscom recommends using a mobile phone solution for (elevator) emergency telephony. Swisscom recommends using a mobile phone solution for (elevator) emergency telephony for availability reasons. The emergency power supplies (UPS) of the mobile communications infrastructure are designed for a power outage of up to 60 minutes. Swisscom offers all the necessary information on the subject of lift emergency telephony on its own website:
[https://www.swisscom.ch/de/about/unternehmen/netz/all-ip/lifttelefon.html](https://www.swisscom.ch/de/about/unternehmen/netz/all-ip/ lifttelephone.html)
Waiting is a very bad idea. As the transition to the new banknotes has shown, suppliers/manufacturers are always lagging behind when it comes to a technological change. The end customer then has to bear the consequences…