A two-and-a-half hour disruption of telephone service in greater Portland and other parts of the state this morning was unrelated to problems within the same network last week, according to OTT Communications.

The disruption began this morning at about 9 and was corrected at 11:30 a.m., said Jon Henderson, vice president of sales and marketing at OTT, which is the parent company of Mid-Maine and Pine Tree.

Henderson said the company is still looking into the cause of the disruption but said a backup system activated and led to customers having difficulty making outgoing calls even though they could receive calls.

“One side of that redundant network took a hit. While the network didn’t go down, it did cause some of our processors and core switches to basically get confused,” Henderson said.

Customers served by the OTT network experienced similar phone problems last Tuesday afternoon. Henderson said that disruption appeared to be caused by a lightning strike that effectively severed a cable. “The situations are unrelated to each other,” he said.

The disruption apparently affected many Time Warner digital telephone customers, a spokesman said this morning.

“We are currently experiencing a digital phone service outage across the state of Maine and New Hampshire and are working closely with our local network providers to identify and resolve the issue,” said Peter DeWitt.

It did not affect FairPoint and other telephone companies such as GWI that are not affiliated with OTT.

11:42 a.m.

Telephone service has been disrupted in the Portland area for the second time in a week.

The Cumberland County Sheriff’s Department said it cannot make outgoing calls from its headquarters and jail in Portland and the service is also affected in Windham and Gorham. Incoming calls and emergency 911 calls are not affected by the problem.

Employees at the Portland Press Herald newsroom also cannot place outgoing calls but are receiving calls.

Land line callers were greeted with a recording that said, “We’re sorry, due to heavy calling we cannot complete your call at this time.”

Peter DeWitt, a spokesoman for Time Warner, said in an e-mail that the disruption is having wisdespread impacts on digital customers.

“We are currently experiencing a digital phone service outage across the state of Maine and New Hampshire and are working closely with our local network providers to identify and resolve the issue,” DeWitt wrote.

It is unclear what is causing the disruption. Representatives of FairPoint and OTT Communications could not be reached immediately.

The disruption is much like one that lasted about two hours last Tuesday afternoon. In that case, officials said a severed cable apparently was the cause of a disruption that affected Time Warner Cable digital phone customers as well as customers served by small telephone company carriers including Mid-Maine Communications and Pine Tree Networks.