NEWTON, Mass. -- A Newton doctor's office is trying to determine who hacked into their phone system and made calls overseas, including the Middle East.

NewsCenter 5's Jim Boyd reported that Wellesley Woman's Care Manager Pam Liep said that she learned of the problem about nine months ago. Her long distance carriers notified them that someone called the Philippines.

"We never call anywhere other than the United States. We don't make international calls," she said.

The office is adjacent to Newton-Wellesley Hospital. Liep said that the calls were made overnight and on weekends when the office is closed.

More than $26,000 in calls have been made since February, but Liep was more concerned about who made the calls.

"With everything that you hear about, I was concerned about terrorism. Were they talking to someone and going through our voice mail or phone system?" she said.

Liep said that AT & T and Verizon said that the problem is most likely with someone hacking into the office's voice mail system. The carriers have made adjustments, and the office will not be held responsible for the bill.

"Answering machines, voice mail services and administrative functions are highly susceptible to hackers and phone hijackers," Verizon said in a statement. "The best defense is to establish passwords that are difficult to hack and to change them often."