2Using a TelephoneTo the Iridium system, you can connect a PBX switchboard or aPSTN telephone. When using a telephone, many of the system’smore advanced features, like e.g. the security lock function, are notaccessible.Telephone call syntaxFor external calls, entering a telephone number on a PSTNtelephone follows the syntax of this example:1. External call 02. Prefix for automatic call 0 03. Country code, e.g. 4 54. Area code, e.g. 7 05. Subscriber’s number, e.g. 1 3 7 0 0 06. Confirmation #For internal calls, entering a telephone number on a PSTNtelephone follows the syntax of this example:1. Internal number, e.g. 3 4 42. Confirmation #Making a Call1. Lift the phone and listen for the tone signalling:Busy tone: Hang up and try again later.Ready tone: The telephone is ready for calling.2. Enter the wanted number, including the prefix for external call,prefix for automatic call, country code, and area code. Anexample of a Danish subscriber:0 0 0 4 5 7 0 1 3 7 0 0 03. To confirm you want to make the call, press: #4. Wait for your call to be answered.Answering a Callis done exactly as if it was an ordinary telephone call: Pick up thephone and answer the call.