Lakeisha Preston speaks in acronyms. Working the phones at federal contractor Maximus in Hattiesburg, Mississippi, she drops them as if they were name brands—MSP (Medicare Secondary Payee), ESRD (End Stage Renal Disease) coverage, and CMN (Certificate of Medical Necessity).

As she patiently explains these terms to callers who want to sign up for Medicare or enroll in the Affordable Care Act’s health insurance exchange, Preston keeps an eye on the clock to move to the next caller in the queue.