Xtra suffered an outage lasting six hours and affecting most of Wellington and the South Island on Monday, due to a lack of IP addresses.
Xtra assigns dynamic IP addresses to its JetStream customers, however at noon on Monday its allocated pool ran dry, due in part to a surge in JetStream customers, according to Xtra spokeswoman Anna Kermode.
"Demand for IP numbers outstripped supply. We managed to get things back to normal by six o'clock that night".
Kermode says Xtra isn't considering moving to the new numbering scheme IP version 6 (IPv6) in the near future.
"None of the ISPs are," she says.