Question: what are the types of telephone communication?
Answer: 3.1 PSTN Line (Analogue) 3.2 Common Issues with PSTN (Analogue) Telephone Lines. 3.3 Multiline. 3.4 Digital Lines. 3.5 ISDN2. 3.6 ISDN30. 3.7 Advantages and Disadvantages of ISDN. 3.8 SIP - Session Initiation Protocol Trunking.