They tell lies!!!
If security is the height of the issue, then consider this; Huawei claims their products are up to scratch but in a recent contract in Tahiti, they lied about their products meeting EU standards. My understanding is that they believe (arrogantly) that just because their equipment meets Chinese standard then it should be accepted as meeting all other standard. They're now required by the client to pull their equipment, to be replaced by a third party equipment because Tahiti is a French territory and hence required to meet EU standards but more specifically because they lied (there's the face of the Chinese). If they can get away with it, they will even if they have to lie through their teeth, or should I say, FACE!
Biting the hand that feeds IT
