Telstra will shed more than 400 call centre positions throughout Australia, with Townsville in northern Queensland the hardest hit by the staff reductions.
According to the Communication Workers Union, most of the proposed redundancies will take place in Telstra's customer service delivery team.
The telco is planning to close the Perth assurance centre, the union said. Another 178 positions would go from the assurance centre in Townsville.
The union claimed reductions would also be made in CSD asset management, the global contact centre group, Telstra business, IP delivery and ITS.
Telstra is understood to be relocating the positions to the Phillipines.
The telco has been contacted for comment.
"However we are creating 138 new roles and 11 roles will transition from Ballarat to Melbourne," a Telstra spokesman told Fairfax.
"We don't take these decisions lightly and our focus at the moment is working through the proposed changes with our staff, including hearing their feedback on the proposals."
Telstra cut 64 jobs from its Ballarat offices in February.
Mid last year it revealed it would outsource almost 700 jobs to India to help to boost its presence in the region.
The telco also heavily restructured its network application services and enterprise divisions to target growth in Asia towards the end of 2014.
At its annual investor day conference yesterday, Telstra signalled the beginning of a major cost-cutting drive within the telco, including "substantial reductions in staff overheads".