A report last week that China’s big three telcos would roll out a number portability system next month — more than a decade behind the U.S. — got me thinking about just how identical the trio of China Mobile, China Unicom, and China Telecom are. All three are big state-owned behemoths, led by faceless bureaucrats who move seamlessly between the carriers and also their regulator.

After years on the China tech beat, I’ve found it’s more useful to think of these three as separate limbs on the same body, rather than the three separately listed companies that Beijing wants us to see.

But there must be some differences between this trio, as evidenced by the much higher valuation investors have given to China Unicom compared with the much larger China Mobile. To understand the difference, company watchers shouldn’t look at the companies themselves, but rather at their regulator, the Ministry of Industry and Information Technology (MIIT).

Right now the regulator seems to be favoring Unicom and China Telecom, which collectively control about 40% of the market compared with China Mobile’s much larger 60%. The latest evidence of that favoritism lies in the regulator’s decision to let Unicom and China Telecom co-build a new 5G network, even as China Mobile will be forced to build its own separate network. That move alone could save each of the smaller telcos tens of billions of dollars in expense, which should filter down to their bottom lines.

For more on the story, read Doug’s latest Tech Talk column published today on Caixin Global.

Related: China Telecom Backs 5G Network Sharing With Rivals