Huawei and ZTE have been effectively barred from infrastructure deals with major US telcos since Sprint was pressurized to drop the former from its network in 2013, when it was migrating from WiMAX (which Huawei did supply) to LTE. While the ban is not definitive in official terms, there are now calls from some parts of the US Congress to make it so. The continuing climate of suspicion and hostility towards the Chinese vendors was highlighted again earlier this month when a reported handset deal at AT&T, for Huawei’s flagship smartphones, failed to materialize at the Consumer Electronics Show. Officially, the pressure on operators to avoid these vendors is down to national security concerns that they could use their networks…