The Communications Workers Union (CWU) is seeking clarification about the possible buy-out of Eircom.
The Australian investment firm Babcock and Brown has recently increased its stake in the company and is believed to be poised to launch a takeover bid.
The CWU fears Babcock and Brown may break the company up and sell off the retail and mobile phone sections to concentrate on network operations.
Spokesman Steve Fitzpatrick said last night: "There are 7,000 people with mortgages and families out there wondering how that's going to affect them."