Telecom New Zealand is to consolidate its Australian operations, folding TNZA, its business services division, into AAPT.
Telecom spokesman, John Goulter, said: "It's really just to present a clean face to the market, a clear brand. At the moment, AAPT and TNZA are both pursuing business customers and we want to make it more connected with the AAPT brand."
Customers of TNZA include the Commonwealth Bank, with which it has a five-year voice and data outsourcing deal.
Asked what the future of TNZA was, Goulter said: "The full details are still being worked through, but the TNZA brand will publicly retreat and become more subsumed into AAPT."
He said it was a branding rather than cost-cutting move, although possibly there would be some job adjustments, but they would be minor.
The two companies' premises will be rationalised.
Telecom NZ chief information officer, Mark Ratcliffe, will travel to Australia to work temporarily on the merger, but will retain his New Zealand role.
Ratcliffe's move will be similar to that made by chief financial officer, Marko Bogoievski, earlier this year to temporarily head AAPT, while remaining chief financial officer in New Zealand.
Australian telecoms analyst, Paul Budde, said the move didn't surprise him.
"If you look at Telecom, international traffic is critical for its core business," Budde said. "Having two separate arms could lead to confusion in the market."
The merger would create better conditions for growing trans-Tasman traffic, he said.