PBX installation©2001 Nokia Mobile Phones. All rights reserved. 25Functionality in extension modeOutgoing call on the extension line, mode A1 The user keys in the number of the extension where the Nokia 22 is connect-ed.2 The terminal answers the call and provides a dial tone.3 The user keys in the number of the B subscriber.4 The terminal establishes the call.Outgoing call on the extension line, mode B1 The user keys in the number of the extension where the Nokia 22 is connect-ed.2 The terminal answers the call and provides silence.3 The user keys in the number of the B subscriber.4 The terminal establishes the call.The terminal can be configured to change or add a mobile prefix to the number.Thus, it can provide for example cost-effective routing. For further informationabout the AAC, see “ Automatic Area Code (AAC) and routing” on page 16.Note: Some exceptions like emergency numbers have to be taken intoaccount. For details, see “8. Security information” on page 43.Incoming call on the extension line, mode A1 The Nokia 22 answers the incoming call and opens the extension line.2 The PBX provides a dial tone.3 The user enters an extension number or outgoing number.4 The PBX routes the call as it would come from an extension telephone.Incoming call on the extension line, mode B1 The Nokia 22 answers the incoming call and opens the extension line.2 The terminal sends a pre-defined number to the PBX extension.3 The B subscriber answers.