SIP Provider Deutsche Telekom, SIP Trunk (DE) (kb4856)

The information in this article applies to:

  • SwyxWare 2015

[ Summary | Information | Links ]


Information und configuration hints for SIP provider Deutsche Telekom, SIP Trunk (Germany).


General information

Deutsche Telekom is offering a SIP trunk with user authentication. You have received information about UserID, UserName and UserPassword, whereas the naming may differ, or you might have only received UserName and -password. In this case, UserID and UserName are identical. 

For a reliable operation of a SwyxWare on a Telekom SIP Trunk, at least SwyxWare2015R30.5 with a CHF has to be installed.

During creation of the SIP Trunkgroup, profile 'Telekom Trunk TCP (DE)' must be selected.
If encryption is required, profile 'Telekom Trunk TLS (DE)' must be selected. Currently (15/09/2016) it is nmandatory to import two Telekom certificates into the Windows-Certificate store of the SwyxWare server. Additional information (in German) can be found as download link at the end of this article.

Required information:

  • Access number (previously T-Online Number) or Telephony-Username, i.e. 11223344
  • Personal password for the Telekom SIP Trunk
  • assigned number range, i.e. +49 401122330 - +49 4011223339

This information is provided by Deutsche Telekom when the connection is created or can be accessed through the Telekom customer center.

As UserId for the created SIP Trunk, the first number of the available number range has to be configured, i.e. +49401122330. User name is the Access number (previously T-Online Number) or Telephony-Username respectively.

Tested Features

  • Incoming/outgoing national calls
  • Incoming/outgoing international calls
  • Correct Calling Line Identificaion (CLI) on national and international calls
  • CLIP No Screening
  • Holding and retrieving calls
  • Toggeling between two calls
  • Call transfer
  • Call forwarding
  • Conferencing
  • Mutually supported codecs:
    • G.711a
    • G.711u
  • Incoming/outgoing DTMF signaling in accordance with via RFC2833
  • FAX transmission via G.711

FAX transmission


The Telekom SIP Trunk does not support the T.38 protocol, which is strongly recommended for FAX transmission in an IP environment. The alternative method for FAX transmission via G.711 is supported from SwyxWare2015R3 on. In oder to prevent the intended T.38 stream switch, it is necessary to remove the T.38 codec from the list of supported codecs.
Note: Quality and reliability of a FAX transmission via G.711 strongly depends on the end-to-end network connection. Since the control and redundancy information from the T.38 protocol are missing, especially the transmission of larger documents may fail.

Test date:
02/09/2016 with SwyxWare2015R30.5

Further tested SIP providers


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