Or, you could just use Wire, created by the original creater of Skype, which also uses Signal's open source encryption code, but it is not a temporary opt-in feature, rather it is the default all the time for chats and calls. Or you could just use Signal.
I just don't trust Microsoft. They are known to have already in the past helped the NSA work around the encryption in their own products, to give it customer information (revealed in the Snowden leaks).
I'm disappointed that Signal is working with a company like this that can't be trusted. Just as they worked with WhatsApp which is closed source and offers no way for third parties to verify that they are really using Signal's encryption. Signal is a great product. But they make some ethically bad choices about companies they are willing to work with. I know they want their code to be adopted more widely, but this is not the way. It undermines people's ability to trust Signal itself.