They dominate Auckland’s skyline; one in the central city and the other atop the Waitakere mountain range west of the city.
One, the Sky Tower, is instantly recognisable and the other, BCL's tower at Waiatarua in the Waitakeres, is lesser known but visible to anyone in Auckland who looks west.
Both towers have been transmitting TV signals since they were built — 1965 in the case of Waiatarua and 1996 for the Sky Tower. The top of Sky Tower is 360m above sea level and the Waiatarua tower 349m, though geography helps — the structure itself is only 122m tall.
Television and radio have long maintained transmission hosting arrangements with the two towers’ operators, but mobile telecommunications and ISPs are also hosted at both sites.
Most players in the mobile industry use the Sky Tower, including Vodafone, Telecom and Walker Wireless.
BCL spokesperson Anna Radford says the TVNZ subsidiary does not want to divulge customers using Waiat-arua, but Walker Wire-less is one of several telcos that use it, as does ISP Ihug.
Walker managing director Bob Smith says both towers are “quite important” for the mobile internet operator.
“We broadcast off the Sky Tower with our current technology and have all our IP backbone there — we terminate our international traffic there.”
The new wideband CDMA technology Walker is trying out with Vodafone is unlikely to be broadcast from either tower, however, “because they’re both a bit high”.
For ISPs, the Sky Tower is vital to their provision of services to Aucklanders; through APE, the Auckland Peering Exchange run by network operator CityLink, approximately 30 ISPs exchange traffic for free (assisted by a switch donated by Cisco), according to CityLink’s Wellington-based technical director, Richard Naylor.
“It carries a lot of traffic.”
One ISP that makes heavy use of both the Sky Tower and Waiatarua is Ihug, which uses the towers for its Ultra service, providing fast wireless downloads and much slower dial-up uploads.
Ihug sales and marketing manager Tim Wood says if it wasn’t for the towers, “we’d be struggling to get the coverage we do”.
Ihug covers 70% of Auckland from the Sky Tower and 15% from Waiatarua, Wood says.
The Sky Tower didn’t give Ihug coverage of the beaches on Auckland’s North Shore, he says, so Waiatarua was added as a transmission site after the company initially chose the Sky Tower.
The construction of Sky’s tower was fortuitious for Ihug, Wood says. “We launched at the same time it was built.”
BCL technical director Keith Ladyman says Waiatarua chews through $250,000 worth of power a year; the figure for the Sky Tower was unavailable but we can assume its figure is much higher, given that it’s lit up every night.