Telecommunications Users Association chief executive Paul Brislen is leaving the job after three and a half years.
Brislen joined TUANZ - which advocates for consumers in telecommunications issues - in 2010 and has been a high-profile voice in the sector over that time.
"Paul joined TUANZ in late 2010 and has overseen dramatic changes to both TUANZ and to the wider telecommunications market as well," TUANZ said this morning.
"In that time we've seen the break-up of Telecom, the launch of a new Telecommunications Act and the roll outs of both Ultra Fast Broadband and Rural Broadband Initiatives, the introduction of new GCSB and telecommunications interception laws, the introduction of a new Telecommunications Commissioner and the start of the final chapter of copper regulation," the association said.
Brislen in a press statement said the last three years had been a "tremendous learning curve" for him.
On Twitter Brislen indicated he could not reveal where he was moving to but that it was a "new adventure" with lots of "scary" moments.
Other media have reported Brislen is moving into a PR role.
Brislen, who lives in Auckland, joined TUANZ after working in PR for Vodafone.
TUANZ chair Pat O'Connell said the search for a new CEO begins immediately.