The wiretapping scandal you are referring to is known as "The Athens Affair" and has to do with infiltration of Ericsson software exchanges by experts on how the software is working. Vodafone is/was the one to blame here and it wasn't a fault of the software provided by Ericsson. More info here: https://spectrum.ieee.org/telecom/security/the-athens-affair

The CLOUD Act is a mechanism for legal authorities to compel companies to produce data they hold, even if it is stored on servers outside the US. I don't think it's fair to characterise that as a backdoor.

The US can use the front door and nobody can stop them. That's the dividend of being a superpower. It's the good old gunboat diplomacy for the 21st century. What are local potentates going to do against America?