Mobile service has been intermittent and customers have reported call drop-outs and difficulty accessing the internet. Optus does not know how many customers have been affected by the works.

"Optus is currently undertaking necessary upgrades to the mobile tower in Rutherford to support 4G services," an Optus spokeswoman said.

"Once complete, customers in the area will faster internet, smoother streaming and better indoor coverage.

"As a result of the work, some Optus customers in Rutherford are experiencing intermittent interruptions to their mobile voice and internet services.

"We apologise to our customers for any inconvenience and appreciate their patience as we roll out 4G services in the area."

Works are scheduled to be completed by Monday July 13.