Wondering why your Wollongong mobile reception seems a bit off?

The telco giant's mobile phone tower at Fernhill has been switched off during the day so another company's contractors can make repairs to the structure.

Telstra informed some customers on Thursday, April 25, that it would be switching off the tower between April 20 and 26 and this would affect phone use.

The tower is at the Fairy Meadow end of Pringle Rd, on commercial property next door to the Illawarra Meat Co.

"From the 20th-26^th of April, we will be switching off our Fernhill mobile site during the day, this is to allow for third party work on the tower," the SMS from Telstra said on Thursday morning.

"As a result, a reduction in Telstra mobile coverage will occur during this time."

But while the message wasn't received by many until Thursday morning, there wasn't many work being done onsite as Australia observed the Anzac Day public holiday.

The turned-off tower would be likely to affect customers in Wollongong's north, whose mobile phone network is Telstra or one of the retailers which use the major telco's network, such as Amaysim or Boost Mobile.

From Friday reception should be back to its normal levels once the work has been completed.

Elsewhere Wollongong's northern suburbs, an application is in for a new mobile phone tower at Ocean Park in Woonona to replace the current tower used for the Optus and Vodafone networks.

This is part of the rollout of the 5G network which requires more equipment and thus a stronger pole.

The development application for the new tower states that if it were removed and not replaced, this would create a "mobile network hole" in the area.