When a security analysis was done of Chinese parts of the Dutch mobile network, that was pretty much the conclusion: Chinese vendors deliver software and components full of vulnerabilities, but none of them seem to be intentional.

Since then there has been a movement to reduce Chinese vendors in general our if security concerns, as well as to improve the security posture of the mobile networks by doing things like "encrypting connections" and "switching away from telnet".

On the other hand, the Chinese managed to break into the US wiretapping system, so it's not like other networks aren't vulnerable either.