When signing a contract in Switzerland, the first few days have their own rules. If the contract does not specify otherwise, the trial period is one month. During that month, either party can terminate the contract with only 7 days' notice, and that notice can be given at any time, not just at the end of the month.
What surprises a lot of people is what happens if you get sick during the trial period. Unlike what happens afterwards, being on leave does not protect you from immediate dismissal, but it does have an effect: the days off do not count, the probationary period is suspended and extended for the time you were on leave. The same goes for an accident or military service. If you have a one-month trial period and fall down the ladder on the 15th, the trial period is automatically extended on those days.
The trial period may be extended in writing up to a maximum of three months. If the contract stipulates it, that is legal and customary in certain sectors. And one thing that not everyone knows: if you change positions within the same company, or return after a long period of leave, the employer can set a new probationary period for the new role. It's not automatic, but it's allowed.
Once the probationary period is over, the notice becomes one month during the first year, two months from the second to the ninth year, and three months from the tenth year. That is, unless the contract or collective agreement establishes otherwise.