Landline, Internet, EFTPOS and some mobile phone services were out of operation in Tenterfield during business hours on Friday due to damage to fibre optics cables around 70km west of Coffs Harbour.

Though service interruptions were reported from an area spanning from Armidale to north of Tenterfield, Richard Bourne, Telstra Countrywide Area General Manager Northwest NSW, said those in Tenterfield and Glen Innes were the worst affected.

Telstra is currently investigating what caused the damage to the line, but said they could rule out contractor damage.

Deidre Curr and Tony Serafim at Mitre 10 said they were unsure of how the outages would affect businesses around town, but said they probably would have lost some sales due to the loss of EFTPOS transactions.

"We've had no EFTPOS since the start of the day, so we've had to send people away to the bank to get money. Some people were okay with it, and some people weren't happy," Ms Curr said.

"I suppose we have lost some sales because of it."

Telephone services were first interrupted around midnight on Thursday night and most were restored by 9.30pm on Friday night, though some services were still out until midday Saturday.

"Something we would like to remind people is that calls to 000 could still get through on other carriers on the mobile network, even though the Telstra network was down," Mr Bourne said.