"Despite our pro-active efforts to forecast the network traffic Deco Days would generate, we still encountered congestion due to the sheer volume of people at this wildly popular event.
"As a result of the network performance this year, we will be adding additional capacity next year, which could include boosting coverage with a Cell Site on Wheels if needed."
A spokesperson from Spark said although there was a huge influx of people, the network still performed "well".
"We didn't see any problems with calling or texting on our network, but a minority of Spark customers in the area may have experienced a slight degradation of service when trying to use their mobile data on Friday and Saturday during peak times.
"We realise that must have been frustrating and apologise to these customers for any inconvenience caused. As we always do after events like these, we'll review how the network performed and look at what we can do to ensure we iron out any problems for the next event."
It was widely estimated the crowd for the major event in the five-day festival was even bigger than for last year's 30th anniversary.
"They are saying it's the biggest-ever," said Art Deco Trust acting general manager Vicky Rope.
"We do have to look at the infrastructure. The event is big, and we do have to look at it in our debriefing. We and the council to have to take a big look at it."
"But we couldn't be happier with the weekend," she said. "The weather played its part, and we're really pleased Hawke's Bay put on a good weekend."