Why does the big factory receive poor SMS signal in Yanjiao?

There will be a signal covering the receiving area.

In other words, this place has both Beijing signals and Hebei signals. If the signal in Hebei is strong, people will not leave Beijing, but the signal will "cross the border".

Dachang Hui Autonomous County belongs to Langfang City, Hebei Province, located in the Hebei enclave between Beijing and Tianjin in the north-central part of Hebei Province, with a total area of 176.29 square kilometers. It has jurisdiction over five towns, four communities and 10 1 administrative village. The county government is located in Dachang Town. Dachang County is located in the upper reaches of Chaobai River, and Baoqiu River flows through the county from west to east.