AT&T Inc., looking to win approval for its proposed $39 billion acquisition of T-Mobile, is facing a challenge in California where regulators have raised questions about the deal’s effect on consumers and corporate customers.

The state’s Public Utilities Commission has held seven public discussions of the bid, under the oversight of Commissioner Catherine Sandoval. She’s delving into how a merger would affect rural communities, corporations and the evolution of wireless technologies. Through her scrutiny, the 50-year-old antitrust law professor and Rhodes Scholar may help determine whether AT&T’s bid succeeds or fails.