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Bernhard Albler



This page aims to provide an overview of common pstn configurations in Austria. In Austria PSTN connectivity is provided by multiple carriers, mostly via ISDN. FXO is only provided in very rare circumstances. SIP Trunks are provided by some carriers but are not widely available yet.



The Austrian dialplan is a variable length numbering plan, which consists of area codes and subscribers numbers. Area Codes are from 1 to 4 digits in length, subscriber numbers vary even more. Some Numbers (mostly used by companies) allow the use of Direct Inward Dial Extension. If such a number is used, it is up to the company to decide on the length of extensions, meaning that any length can be used.If too long extensions are used, the numbers might not be reachable from some sources. This is especially relevant with regard to number presentation inside of isdn, as stated under "Voice Interfaces and signalling".


A copy of the Austrian dialplan is maintained by the austrian regulatory council at


Emergency Services

The following emergency numbers are commonly used:

  • 122: Fire Brigade
  • 133: Police
  • 144: Ambulance


Generally it is preferred to make emergency service numbers accessible both directly as well as via the trunk access code (e.g. 0122)


Private/PBX Dialplan

"0" is generally used as a trunk access code, resulting in the following schemes:

  • 0+Subscriber Number for local area code dialling
  • 00+ Are Code+ Subscriber: Dialing to other area codes
  • 000 + Country Code + Number: International Destinations


As mentioned before, the length of internal extensions is up to decision by the company which owns the PBX. This also translates to the dialplan. Generally the Attendant is reachable via 3 different ways. Consider the following example: A company has acquired the number +43 (1) 8676776 as their main office number. Then the receptionist / attendant would be reachable via the following

  • Dialing the Main Number without any extension, +43 1 8676776
  • Dialing the Main Number with "0" as the extension, +43 1 8676776 0
  • Dialing any number that is not defined inside of the pbx, e.g. numbers short or longer than the internal numbering plan of the company

Voice Interfaces and signalling

Physical Interfaces

ISDN is the most common access technology for business pstn access. Both BRI and PRI are available and commonly used.

For ISDN BRI Interfaces, use "isdn switch-type basic-net3", for PRI Interfaces use "primary-net5"

Common ISDN BRI Int Config (Should work for most sites):



interface BRI0/0/0
no ip address
isdn switch-type basic-net3
isdn overlap-receiving T302 4000
isdn twait-disable
isdn point-to-point-setup
isdn incoming-voice voice
isdn send-alerting
isdn sending-complete
isdn static-tei 0


Voice Port Config:



voice-port 0/0/0
translation-profile incoming <translation rule>
input gain -1
output attenuation 2
echo-cancel coverage 32
compand-type a-law
cptone AT
timeouts interdigit 5
timeouts wait-release infinity
bearer-cap Speech

ISDN Signalling

ISDN Overlap Sending and Receiving is commonly used in Austria. This poses some challenges with regard to the variable length dialplan is mentioned. The issue is further confounded, because ISDN Switches commonly only send the dialed extension without the main number.


Consider the following example, again using the number +43 1 867 67 76. Let's assume the customer is using 3 digit extensions. The following isdn setup might be received on a bri interface in austria:



Sep 22 19:52:07.336 MET: ISDN BR0/1/0 Q931: RX <- SETUP pd = 8  callref = 0x01 
     Sending Complete
     Bearer Capability i = 0x8090A3
          Standard = CCITT
          Transfer Capability = Speech 
          Transfer Mode = Circuit
          Transfer Rate = 64 kbit/s
     Channel ID i = 0x89
          Exclusive, B1
     Calling Party Number i = 0x2183, '69915600516'
          Plan:ISDN, Type:National


Even though no Called Party Number was transmitted, the setup is valid.


Such a setup could mean two things:

  • The Caller is calling the main number with the indent to speak to the receptionist
  • Further Digits will follow via isdn overlap receiving
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