WEST LEBANON — Phone and internet services were unavailable or disrupted for many Upper Valley town offices, businesses and customers on Tuesday morning.

Some customers of Consolidated Communications, an Illinois-based broadband company, lost internet and phone service during an outage that was mostly in New Hampshire Tuesday.

Some customers completely lost service, while others experienced unreliable service or had issues with certain actions, such as making outgoing calls.

Not all Consolidated Communications customers experienced the disruptions.

A software upgrade issue “that occurred early Tuesday morning” caused the disruptions, Kyle Thweatt, spokesperson for Consolidated Communications, said in a Tuesday email. Thweatt acknowledged that the outage affected “some New Hampshire customers,” but did not provide a number for those affected.

The company is one of the 10 largest fiber internet providers nationwide and provides high-speed internet and phone services in more than 20 states. It serves all of New Hampshire and Vermont.

Among those affected by Tuesday’s outage was the Dartmouth Health, or DH, which has locations in both Vermont and New Hampshire.

DH lost phone service at all of its locations except for Southwestern Vermont Medical Center in Bennington, Vt., Cassidy Smith, a DH spokeswoman, said in a Tuesday email.

The health provider system health discovered the outage around 9 a.m. and was still experiencing issues as of about 2:30 p.m., Smith said.

Although DH experienced phone outages, all of its locations remained open and continued with scheduled appointments and procedures. The outage did not disrupt emergency services, Smith said.

For some municipalities, the outage halted municipal operations. Charlestown town offices closed at 11 a.m. Tuesday due to “internet connectivity issues,” which meant the town could not process requests from the community, according to an email announcement.

Claremont also appeared to be particularly hard hit, with the Claremont School District and Claremont Savings Bank experiencing disruptions.

“While the outage may cause some temporary inconvenience, we want to assure you that we are taking steps to minimize disruptions to our students’ learning,” the Claremont School District wrote in a Facebook post.

Internet service was restored to the school district around 12:45 p.m., Superintendent Chris Pratt said in a Tuesday email.

Claremont Savings Bank also reported disruptions via Facebook. The bank reported that there were limited banking services available at its West Lebanon and Claremont locations, with Claremont’s drive-through on Washington Street unavailable.

The post has since been deleted, but it was updated to reflect that service had been restored before being deleted. The bank did not respond to a request for comment by deadline.

Despite issues around the city, local government offices did not experience disruptions “as far as I know,” City Manager Yoshi Manale said via email.

In other parts of the Upper Valley, service was unreliable. Woodsville Guaranty Savings Bank was “unable to make outbound calls, and incoming calls are reaching us intermittently,” according to a 12:04 p.m. Facebook post.

As of mid-afternoon Tuesday, Thweatt said some customers were still experiencing interruptions, while others had had service restored.

Consolidated Communications was working with vendors to revert the upgrade and restore services “as quickly as possible.”

“We understand service disruptions are frustrating, and we appreciate our customers’ patience while we work to bring services back online,” Thweatt said.

Clare Shanahan can be reached at cshanahan@vnews.com or 603-727-3216.