Telecom is to consolidate its Australian operations, folding TNZA, its business services division, into AAPT.
Telecom spokesman John Goulter says "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 is, Goulter says "the full details are still being worked through, but the TNZA brand will publicly retreat and become more subsumed into AAPT".
He says it's a branding rather than cost-cutting move, though "possibly, there will be some job adjustments, but they'll be pretty minor".
The two companies' premises are to be rationalised, however.
Telecom NZ chief information officer Mark Ratcliffe will travel to Australia to work temporarily on the merger, while retaining 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 says the move doesn't surprise him.
"If you look at Telecom, international traffic is critical for its core business. Having two separate arms could lead to confusion in the market."
The merger will create better conditions for growing trans-Tasman traffic, he says.