"Since June 12 there have been an increasing number of speed issues experienced by Exetel users connected to Exetel via the Optus ADSL [backhaul] network," Exetel admitted in a recent post to its online customer forums.
The ISP said it had started using Optus' backbone network links (called "backhaul") as it prepared to start reselling services based on Optus' new AU$150 million ADSL2+ broadband network. Exetel will migrate many of its customers from Telstra's ADSL network to Optus' hardware.
However the move appears to have backfired, with one ZDNet Australia reader comparing his current broadband speeds to those available under dial-up hardware.
Exetel blamed the problems on congestion in the Optus network as the provider transitions to a more modern hardware platform.
"The fundamental issue appears to be that Optus' plans to move their national ADSL backhaul from an ATM-based network to a [Gigabit Ethernet] based network has encountered a series of delays," the ISP said.
The ISP added it had met with Optus "several times" to determine when the current issues would be resolved.
"At this time it appears unlikely that Optus will deploy the required additional backhaul bandwidth before July 7," said Exetel.
A spokesperson from Optus said they were investigating the issue.
While Exetel said it had itself implemented a number of workarounds, including restricting peer to peer traffic, the ZDNet Australia reader said passing the buck to Optus wasn't good enough.
"This changeover was poorly planned by Exetel, and should have been assessed prior to the Optus backhaul," he said.
No matter the source of the Exetel problems, the issue in general raises significant questions for Optus as it starts to sell wholesale broadband services on the back of its new AU$150 million ADSL network.
Exetel is only the first of what is expected to be a number of ISPs switching to buy wholesale broadband services from Optus rather than Telstra, which currently supplies most of the market.
Optus will need to get its systems and processes bedded down before it starts to bring on board large numbers of end users owned by third parties like Exetel.
Exetel claims to have some 46,000 business, government and residential customers.