"What we're seeing is something akin to the petrol industry. A model I hope the internet market isn't going to follow. There occurs the slightest hint of a wholesale price rise and the providers are sending out letters to their customers telling them they have to pay more," he said.
InternetNZ is a non-profit group that seeks to foster internet use in this country.
Vodafone began sending letters to customers last week about price rises of $4 a month across the majority of its landline and broadband plans.
The change will impact around 300,000 customers, the Auckland-based telco said, and comes into effect from February 1.
Vodafone's price hike will also make its cable and fibre-internet plans more expensive, despite no direct link between copper wholesale prices and the costs for those services.
"It's certainly on shaky ground that Vodafone need to increase their fibre costs when fibre pricing isn't affected at all," Carter said.
Vodafone's move follows Spark signalling price rises of between $2.50 and $4.25 a month across a number of its home-phone and copper-line broadband plans.
The change will impact around 250,000 phone and some 430,000 broadband customers.
While lifting prices for a large chunk of its customers, Spark is reducing what it charges for its "unlimited" broadband service by $10 a month.
The country's biggest internet and phone company said its new prices will come into effect for new and existing customers from the start of February.
Slingshot is also putting up the price of most of its copper-line broadband plans by $4 a month.
