Up to 5,000 staff, mainly from the TELCO's maintenance operations, are walking off the job for 24 hours.
Telstra says emergency call centres won't be affected.
The Communications Electrical Plumbing Union says Telstra's proposed pay rise of four-and-a-half percent over three years is effectively a pay cut, as it is below the current rate of inflation.
And also, workers at distribution centres for the national pharmacy chain Chemists Warehouse have begun indefinite strike action.
The action is taking place at four regional centres in Victoria and Queensland.
Workers are demanding wages and conditions on a par with industry standards; converting workers from casual contracts to permanent staff; and an end to what they call a 'toxic culture' of bullying.
Chemists Warehouse is a privately owned company with around 300 stores across the country.
