Essential Guidance - Standard Phone Lines

PSTN (Analogue)

  • Limited functionality
  • Usually used for FAX and ADSL Services
  • One external line required per phone installed (DDI not supported)
  • Typical installation lead time is 7-10 working days (subject to survey)

ISDN (Digital)

  • Requires a telephone system
  • ISDN2e is suitable for 2 to 8 phone lines
  • ISDN30 is suitable for larger sites with more than 8 simultaneous calls
  • ISDN supports Direct Dial (DDI)
  • Distance limitations exist from the exchange for ISDN30
  • May be an issue in rural locations
  • Typical installation lead time is 20 working days (subject to survey)

SIP Trunking

  • Scalable from a minimum of 1 line
  • Replaces ISDN lines, interfaces to Internet
  • Supports DDI
  • Typical installation lead time is 2 working days (subject to Internet connectivity)