Optus has finally come on board with regards to NBN Co’s wholesale broadband agreement (WBA), which outlines the access terms for companies using the NBN for the next 12 months.

The move by Optus comes after the likes of iiNet and Primus signed onto the WBA last week and now leaves Telstra as the only major telco yet to sign the dotted line.

“Optus today confirmed it has signed the executable NBN Co wholesale broadband agreement,” the company said.

“Optus will continue to engage in constructive dialogue with NBN Co to ensure that outstanding concerns such as regulatory oversight and service assurance levels are adequately addressed in any future long-term version of the WBA.”

While Optus has become the 25^th service provider to accept the WBA, the telco has told ITNews that there are still some outstanding issues that need to be worked out.  

The nation's second largest telco said that while some progress had been made on the issue of regulatory oversight the current agreement was still not fully up to scratch.

 "The focus now is to ensure outstanding concerns are addressed in any future version [of the agreement]," an Optus spokesperson told ITNews.

The outstanding issues no doubt figure in the talks between Optus and the ACCC with regards to Telstra’s structural separation undertaking.

Telstra is expected to sign the WBA once the SSU gets the nod from the competition regulator in February.