Breakdowns in Hawke's Bay District Health Board's internal communication system led to an outage of its external and internal phone lines.
The outage on Friday morning impacted phone lines as well as the DHB's computer network.
A DHB spokeswoman said the issue was not related to hacking and no patients had been impacted.
"The issue was related to two components of its internal network system and was in no way related to any kind of cyber-attack.
"The DHB has processes and procedures in place for events such as this, which were immediately actioned, however, the main call centre line was down for a short time and the DHB apologises for this."
The DHB's system was operational again after 90 minutes.