Sudden storms in NSW have dealt Telstra customers a blow for the second time this month, leaving 3000 fixed phone lines out of order in North Western Sydney.

Power failures on the back of the weekend's wild winds left more than 100,000 western Sydney homes in the dark at the peak of the storms on Saturday, and more than 4500 Telstra users without fixed line phone communication. This morning, over 3000 Sydneysiders are still unable to use their phones.

"Back-up generators have kept the majority of services working. Telstra has been working around the clock to restore services - taking generators to sites and boosting power then moving on to the next. In the last 24 hours we have restored almost 1,000 services," a Telstra spokesperson told ZDNet Australia.

There are also a number of Telstra mobile base stations affected in Sydney, including Somersby, Cowan area, Toongabbie, Blacktown, Castle Hill and Mudgee, again caused by power failures resulting in transmission failure, the national carrier confirmed.

"Our networks are vital to our business - we are firmly committed to protecting them. We work continually to protect the network primarily through preventative measures," the spokesperson said.

In the case of waterproofing, Telstra claims to do a number of things.

• The majority of large cables are under constant air pressure to keep them dry
• Newer cables in the network have a gel within the cable that stops water getting in
• Telephone lines come together at a 'joint'- often housed in a street pit. Joint enclosures are already waterproof but Telstra claims to be investigating improved joint enclosures that are even more robust.

"Despite our best efforts, heavy and continuous rain can still cause a problem for phone services, just as it does electrical services. The fact that we have not had this much rain for years has accentuated the effects on the network. This same issue has affected storm water drains across NSW, which have flooded (because the build up hasn't been washed away) and overflowed into Telstra street pits," the spokesperson said.

According to Telstra, the restoration time for the 3000 phone lines currently affected, will depend entirely on getting mains power back up and running. -In the meantime we are maintaining service wherever possible using generators and batteries. Once power supply is restored we expect to have phones restored within a day," the spokesperson said.

Telstra's spokesperson said the storm damage hadn't been as severe at the flood damage to services earlier this month, when up to 10,000 fixed phone line services obliterated across the state.

However,the electrical damage alone, which might mean replacing some equipment, could run into the thousands or tens of thousands of dollars and there would be 100's of hours of labour hours involved in the restorations, according to Telstra's spokesperson.

Copyright © 2009 CBS Interactive, a CBS Company. All Rights Reserved.
ZDNET is a registered service mark of CBS Interactive. ZDNET Logo is a service mark of CBS Interactive.