Despite those criticisms, Britain's conditional seal of approval is important for Huawei as a counterbalance to American pressure.
Germany and Italy also seem reluctant to ban it. Germany recently opened a test laboratory similar to the one in Britain.
New Zealand has blocked an application by Spark, a phone network, to use Huawei's gear on national-security grounds.
But it has not blacklisted the firm outright. Poland, which arrested both a Chinese Huawei employee
and one of its own citizens on espionage charges in January, has pleaded for Western unity.
Huawei itself points out that no evidence of back doors has ever been found and argues that implementing them would be commercial suicide.
The firm's tone is both conciliatory and defiant. Mr Ren has described American concerns as "politically motivated"
and said that the country will be unable to "crush" his firm. Huawei has said it will address Britain's criticisms but that doing so will take years.
The arguments are about more than coding. Huawei is a Chinese champion.
As an aspirant superpower, China sees technology as a vital national interest.
The incumbent superpower, America, thinks similarly and a technological cold war is developing between the two.
Britain, pondering its place in the world after Brexit, is a traditional ally of America but is also courting Chinese investment.
Canada's position is the trickiest of all, at least for now.
Its government must decide by March 1st whether Ms Meng's extradition hearing can go ahead.
In what are widely seen as reprisals for her arrest, two Canadian citizens have been detained in China.
A third has been sentenced to death for drug-smuggling, after initially being sentenced to 15 years in prison.
Expect the temperature to carry on rising.