On AT&T’s Q2 2026 earnings call, CEO John Stankey said, “We’re converting market-by-market, and we’re pretty much getting to the back end of that now,” referring to the integration of systems from AT&T’s acquisition of the Mass Markets fiber portion of Lumen Technologies’ business. All this in less than a year since the deal closed on February 2, 2026.

“Pretty much” means considerably more than porting over customer records and billing information. In Stankey’s own words, it means “converting all the infrastructure, all the branding, all the support systems that we have with customers, all the methodologies the technicians use when they show up in a house, all the CPE that a customer gets.” CPE means customer premises equipment, for anyone not steeped in telecommunications jargon.

Roughly 1.1 million of Lumen’s former CenturyLink and Quantum Fiber subscribers are part of this conversion. Stankey didn’t give a completion percentage, so we don’t know exactly how many of those 1.1 million have crossed over so far, only that AT&T is pretty much to the back end. Even so, getting most of a job that size done in well under a year is genuine progress, and a daunting one for even a well-resourced, experienced company.

“Pretty much” also means some former Lumen customers are still getting bills under the old CenturyLink or Quantum Fiber brands. That’s multiple billing systems running in parallel for many months now. Even so, that doesn’t read as AT&T slacking or falling behind. Stankey’s own phrase, market-by-market, reads as leadership being honest with itself about how long this kind of work takes, even when it’s going well.

AT&T never committed ahead of time to one anticipated completion date. They’ve converted one market at a time, on a rolling basis. That’s much closer to the phased, checkpoint-driven approach we recommend than committing to a single go-live date, even one set well off in the future.

It’s not proof AT&T has avoided every pitfall. But it suggests a disciplined approach to avoiding the worst of the Day 101 Problem, and a healthier kind of messaging than declaring victory too early only to explain continuing remediation costs to the board later.

What’s the longest you’ve seen two systems run in parallel after an acquisition close?

Originally posted on LinkedIn.