Can I get fired over the phone?

I recently took on a permanent contract and am currently in my three-month trial period. Last week, while I was out for a walk on my day off, my employer called to tell me that my contract was being terminated. He gave me no explicit reason and didn't even confirm it in writing. I wasn't expecting this and I'm at a loss: is this termination valid?
J. Geneva

Such a termination by telephone is problematic and could be challenged. Under Swiss employment law, article 335b of the Code of Obligations provides that during the trial period either party may terminate the contract by giving seven days' notice, unless otherwise agreed. However, such termination must comply with certain formal and procedural requirements, in particular those relating to notice of termination and the proof that must be provided by the party invoking it.
In a case brought before the Federal Court in 2023, an employer claimed to have terminated a contract during the probationary period by means of a telephone call. However, in the absence of clear and tangible evidence, this termination was not considered validly notified. The employer bears the burden of proving that the termination was actually communicated to the employee, in accordance with the principle laid down in article 8 of the Civil Code. If proof of notification is insufficient or non-existent, the said termination has no legal effect.
In the situation you describe, the absence of written confirmation of the termination leaves some uncertainty as to its validity. Termination, although possible orally, must be clear, unambiguous and capable of being proven. The telephone call you mention - which was not followed up by a written document - does not meet these criteria. It should be noted that the employer could also have organised a prior interview to clarify the reasons for the termination, although this is not a strict obligation.
Our Supreme Court also emphasises that mere allegations are not enough to justify such an important legal act. If the employer claims that the contract has come to an end, it must provide solid evidence of this, such as written documents or credible testimony, so that you can claim that your employment contract is still in force and demand payment of the wages owed to you. This includes not only the salary that is still running, but also any untaken holiday or other benefits provided for in your contract.
You would be well advised to clarify your status with your employer as soon as possible, because an ambiguous situation is a source of problems, whereas each party to an employment contract is expected to behave in good faith.