Users have discovered the dual-band CDMA-analogue handsets suffer chronic battery drainage when using the analogue network.
The analogue network is due to be phased out by the end of this year, Telstra said. The old analogue network is currently used only in areas where the CDMA network has not been rolled out, according to Telstra.
The first analogue closure was on December 31 and by mid-year the network will be fully closed in NSW.
"What's currently happening is that the CDMA handsets operate in dual mode," explained the Telstra spokesperson.
"When it locks onto analogue, it drains the battery. They can't use the phone for as long," he explained.
As a temporary work-around, Telstra is allowing customers who have disconnected their analogue phones to reconnect for $5 per month.
That means users in areas where CDMA coverage is not complete will also have to carry their old analogue handsets to receive full coverage, Telstra said.
The spokesman denied Telstra was switching the analogue network back on.
"We do not have the power to reopen the network, nor are we trying to change the timing of the network closure," the spokesperson said. "That's set by federal government legislation."