It would be suicidal for Huawei to ship any eqipment to Western carriers with actual backdoors. European governments usually require through audit of the code that runs their networks and vendors are required to have reproducable builds for the same. The UK government for instance has the Huawei Cyber Security Evaluation Centre[1] responsible for vetting the Huawei equipment that gets used by British carriers. Like TFA says, "The U.K. government said in July it found shortcomings in the process." They did't find any backdoors or any actual vunerebilities but did report "variable engineering quality". Like any large and complex codebase produced by thousands of engineers, parts of the code may be downright ugly but that does not make it malicious.
Anyways, the CSEC report did have its intended effect and now significant resources are being expended to refactor legacy code. Nothing motivates management like a possible loss of revenue from bad PR ;)
Then again the NSA hacked into Huawei HQ[2] so they might know something that others don't. Speaking of which, how is the search for WMDs in Iraq coming along?
1: https://assets.publishing.service.gov.uk/government/uploads/...
2: https://www.nytimes.com/2014/03/23/world/asia/nsa-breached-c...