BNZ has re-signed with Vodafone/TelstraClear for another six years.
The bank, owned by Australia's NAB, has been a TelstraClear client since 2002.
The whole-of-business contract covers network and related services, calling, security services, customer contact centre, enterprise video and voice services, managed services and professional services.
Access to TelstraClear's corporate clients was one of Vodafone's key reasons for buying the Telstra subsidiary in an $840 million deal finalised on October 31.
The deal included a non-compete cause of unspecified duration, plus a five-year contract for Vodafone to service the New Zealand business of Telstra's trans-Tasman clients.
Vodafone said in October that it would continue to run TelstraClear as a separate business during a five or six month assessment period.
Integration will take place over the next 12 months, with the TelstraClear brand phased out altogether within 18 months.