Shortly before 4.35pm, he pulled well off the southbound lane of Te Ngae Rd outside the Eastgate Business Park to take the call.
Alexander Neil Christensen was, meanwhile, travelling from his Te Puke home to work in Rotorua when his car drifted off the road and over the lane marking.
Christensen later told police he could not remember what happened, and that he saw Mr Kolsen's car only at the "last instant".
The force of the impact spun Mr Kolsen's car 180 degrees and he was fatally injured.
Texts from his pregnant partner, Corinne Lodge, went unanswered.
When police knocked on her door at 8.30pm, four hours after he was due home, she thought they had come to tell her Mr Kolsen had been in an accident and was in hospital.
But he was already dead.
Alexandria ("Lexi") Kolsen-Lodge, born on October 13, was with Ms Lodge in Rotorua District Court yesterday morning as Christensen stood in the dock with head bowed before Judge Philip Cooper.
Sentencing Christensen on a charge of careless driving causing death, Judge Cooper told him: "This is a case where there was not a high degree of carelessness, but there were utterly tragic consequences."
He banned Christensen from driving for nine months and ordered him to pay $5560 to Ms Lodge and the same amount to Ms Collins.
"Of course, no amount of money will bring Mr Kolsen back ... but that sum may assist the people he's left behind."
Afterwards, Ms Lodge said attending the sentencing was something she "had to do ... so I could say to Lexi that I did everything I could".
She had made her feelings clear to Christensen when he earlier met her to express his remorse.
"I just wanted him to know that my baby was going to grow up without even knowing her father. I wanted him to know how that really affected me and my family."
She told the Herald Christensen's reparation fell short. "For the father of three young children, one who he didn't even meet, I don't think that's enough."
But she was certain of one thing: "If I ever get a phone call on my mobile, I won't be pulling over to answer it, no way."
A police spokeswoman said it was not common that crashes resulted from motorists pulling over to take calls.
Using a hand-held cellphone while driving was outlawed in November 2009 in bid to improve road safety.
Rotorua police area tactical response manager Inspector Ed Van Den Broek urged all motorists to stay alert and watch the road.
"It's tragic what's happened, but it could have easily been avoided."
- Additional reporting: APNZ
