Phone users may occasionally hear tones associated with fax machines and modems. Faults in customer handsets or other equipment connected to the network can also cause high pitched sounds to be heard in the ear piece of a phone or headset. On very rare occasions, these may cause damage to the listener's hearing. To minimise this risk, we recommend that you follow these simple steps:

• if you hear a computer or fax signal when ringing, hang up immediately and check that you have dialled the right number, or switch the call to a modem or fax machine
• do not use a faulty phone when reporting faults
• disconnect faulty phone equipment and return it to the supplier for repair
• use ACA labelled headsets which incorporate acoustic shriek protection
• set the volume on your phone at the minimum level possible.

You may suffer an injury using your phone, fax, computer or other electrical equipment during a thunderstorm. In extreme cases this may be fatal. If you must use your phone during a thunderstorm because of an emergency, then to reduce this risk:

• keep the call as brief as possible
• do not touch electrical appliances, metal fixtures or brick or concrete walls
• do not stand in bare feet on uncovered concrete floors.

When indoors, hands free and cordless phones may be safely used subject to not touching the base unit. Likewise a handheld mobile phone may be used provided the phone is not on a charger and not connected to an external aerial.

When outdoors during a thunderstorm, the Australian Lightning Protection Standard, AS1768, recommends you don't carry metallic objects, such as umbrellas, and you remove metallic jewellery particularly from the upper body. Similarly, Telstra recommends against using a cordless or mobile phone outdoors in an unprotected area. However, a hand held mobile phone may be used in a metal bodied vehicle with a metallic roof, provided there are no electrical connections (charger, external aerial, etc.) to the phone. It may also be used with a hands free car kit as long as the user is not touching the phone or kit and has no electrical connection to the phone. Using a Bluetooth wireless connection is another example of safe use when in such a vehicle. Of course, always obey the road rules.

It is also recommended by AS1768 that you do not use a fax or computer, or other mains powered equipment, during a thunderstorm however a battery powered (eg laptop) computer with a wireless connection may be used. Protective devices¹ can be fitted to phone installations to reduce the risk of personal injury during thunderstorms, but due to the high voltage involved in lightning strikes, complete protection cannot be guaranteed. For further information on installing lightning equipment, please visit Contact Us - Home Phones.

Things you need to know

1. These devices are not intended to protect the equipment itself from lightning damage. For protection of your equipment contact the manufacturer or look up "Lightning Protection" in the Yellow Pages. Except for standard phones rented from Telstra, we do not accept liability for lightning damage or power surge damage to any customer owned or rented equipment associated with the phone service. Nevertheless to assist customers in understanding the concepts and to provide guidance in lightning protection Telstra has produced this brochure about Lightning Surges (PDF, 66KB).