It's been around since the invention of the telephone and according to Yellow it still serves a purpose.
Yellow's 018 phone directory receives 8,000 calls a day, or 48,000 per week, but those totals have decreased significantly compared to five years ago when it was receiving around 23,000 calls per day.
The number of calls it receives are declining at around 18 per cent per year.
A spokeswoman for Yellow said the paid phone directory serviced people without access to the internet, and was mostly used by those aged over 30.
"018 provides a fast and convenient way to ask for information and for mobile customers this is followed up with a text," Yellow CEO Darren Linton said.
"Whilst the call volumes have declined we have seen a dramatic shift to mobiles and continue to see growth in sign ups to our VIP service."
Telecommunications Users Association of New Zealand (TUANZ) chief executive Craig Young said the decline of the phone directory was not a surprise.
"People are making fewer phone calls when it comes to these kinds of services," Young said. "These days, with most things online, people can simply Google the name of the company and find the phone number."
An increasing number of people were also getting rid of their landlines, he said, and Yellow needed to look at alternative ways to deliver its information.
"It's reasonably clunky, I think it's still struggling to find the killer app as to how they are going to remain front of mind for people," he said.
"Most people have been using smartphones for a long time now and pretty much know their way around the internet and finding information. Simply, if you can't Google it, at the moment, 018 is probably your last port of call."
Young said the service still served a purpose but would likely faze out over time.
"The call numbers are going to reduce and it may be that that's a particular opportunity for automation. For example, you may ring the number and voice recognition might recognise your voice and be able to tell you without actually having a person at the end of the line," he said.
"It may be one of those things that fades into the sunset or never goes away."
Colleen Ryan, head of strategy at insights agency TRA, said there was a growing trend for younger generations to prefer text to phone communications.
It may be one of those things that fades into the sunset or never goes away.
"What millennials are liking about non-telephone is that put-on pause; not having to respond instantly. They've acquired the habit of lots of texts, lots of emails, lots of WhatsApps to the point that they're now almost nervous of the phone call," Ryan said.
"For business, they are saying they don't really want to talk to call centres."
Ryan said the directory and similar businesses need to adapt to stay relevant.
"It needs to live on the device, it needs not to be something that we go looking for, it possibly needs to integrate and sync current contact lists and really adopt device-driven trends rather than phone-driven trends."
Yellow went through a rebrand in September last year to transform its business into digital advertising agency. The company has refocused on its digital offering and the services it can offer small and medium-sized businesses.
Calls to 018 cost 51 cents using a landline and $1.53 using a mobile and are answered by call centre staff located in the Philippines and New Zealand.