PORTLAND – FairPoint Communications Inc. said Tuesday it was trying to confirm its diagnosis of a software problem that led to interruptions in the Cumberland County Regional Dispatch Center’s 911 system in Windham, affecting residents of 17 communities in the southern Maine county.

“We’re continuing to do some analysis, but we feel we’ve identified the problem,” said spokesman Jeff Nevins. “We’re working with the software vendor to see what went wrong and why it went wrong.”

There have been several instances of prolonged gaps in 911 service for some Cumberland County residents since mid-April, most recently last weekend. Calls since then have gone through a backup 911 system at the Maine State Police communications center in Gray.

The Public Utilities Commission staff wants to be certain the problem has been identified and corrected before it authorizes a return to the Cumberland County system, PUC spokesman Fred Bever said Tuesday.

Confirming the software glitch “is a top priority” for FairPoint, said Nevins. He said the company also is checking Maine’s seven other 911 call centers, which have similar software, to see if any problems could develop. None has occurred so far, he said.

In March, FairPoint completed a $2.3 billion purchase of Verizon Communications’ wired telephone lines and high-speed Internet service in northern New England. The sale transferred about 1.6 million telephone lines and 230,000 high-speed Internet customers in Maine, New Hampshire and Vermont from Verizon to the North Carolina-based company.

Regulatory officials expressed concerns about FairPoint’s financial strength as they reviewed the transaction, and they also sought service quality assurances.

Nevins said Tuesday that 911 call centers in New Hampshire and Vermont use different software and that emergency calls in those states were not affected.

A FairPoint official acknowledged the company should have fixed problems at the Cumberland dispatch center when they first developed. John Smee, director of network operations for FairPoint, said Monday that company officials were “embarrassed.”