Collaboration with VoIP Providers

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About 160 VoIP Providers released for Unify SME Platforms > table

The connection of communication systems to the public network via SIP Trunking can be used instead of or in addition to traditional PSTN trunks. Many VoIP Providers, also known as ITSPs, are offering corresponding services. The following article gives an overview of the SIP trunking features and limitations and lists the Providers, which have been tested and released with the SME platform OpenScape Business.

You did not find your provider? Find out how to get it released!


OpenScape Business has been tested with a large number of Internet telephony providers that support SIP. Continuously new providers are tested, released and included within administration. As the SIP recommendations leave some room for interpretation, there are differences in the range of features supported with a specific provider. In this chapter general information is given which is valid for all SIP Providers.

SIP trunking features

  • Up to 8 active SIP providers and one Internet connection
  • Operation behind another router using STUN (can be configured per provider with current software) - integrated SBC functionality
  • SIP trunking with single numbers (MSN) and up to 30 SIP user accounts (called Internet telephony stations in WBM)
  • Direct Inward Dialing (DID)
  • Comprehensive feature set available e.g.
    • CLIP
    • Hold, Consultation, Toggle
    • Transfer (attended, semi-attended)
    • Ringing group, Call pickup
    • Conference
    • Call Forwarding
    • Call deflection (new in V2R4)
    • DTMF transmission e.g. for voicemail access
    • Location information for emergency calls
  • Simultaneous VoIP connections depending on system and available DSL bandwidth, used Codec and system. G.711 needs up to 92 kbit/s, G.729A needs up to 36 kbit/s in both directions.
  • Automatic fallback to ISDN at SIP trunk failure
  • Voice Codecs G.711 and G.729
  • Fax over IP via T.38
Security Warning - Malicious attacks from the Internet may lead to reduced service quality or toll fraud!
     Please strictly follow these basic rules:
  • Never open up the firewall in an internal or external router e.g. by forwarding port 5060.
    The SME platforms take care of opening the firewall for traffic with the selected VoIP providers. Attacks from other internet addresses are therefore blocked. Opening up the router's firewall would invalidate this security measure.
  • Never configure SIP subscribers at an OpenScape system without a strong password.
    Authentication blocks registration of unauthorised SIP clients. See
  • For diagnostics and SIP provider configuration hints see How to enable blocked SIP Providers.

General Requirements for VoIP

  • LAN with 10/100/1000 MBit/s and no more than 40% network load
  • Separate port on the switch or router for every component in the IP network (no hubs as concentrators)
  • Not more than 50 ms delay in one direction (One Way Delay); not more than 150 ms total delay
  • Not more than 3% packet loss and 20 ms jitter
  • Quality of Service (QoS) support - IEEE 802.p, DiffServ (RFC 2474) or ToS (RFC 791)
  • Sufficient WAN bandwidth (uplink and downlink) for intended simultaneous calls and CODEC
  • External modem or router
  • Intermediate routers shall support quality of service and bandwidth control mechanisms if the WAN link is used for voice and data simultaneously. SIP messages have to be routed transparently.

For interworking with different network configurations and edge devices and how to use STUN please see Network Configuration for VoIP Providers.

Hints for all Providers

  • Concurrent calls via ITSP (depending on the available bandwidth and used Codec).
    • 30 for OpenScape Business X1
    • 60 for OpenScape Business X3 / X5 / X8
    • 180 for OpenScape Business S
  • DTMF transmission
    • outband transport via RFC 2833/RFC4733 is highly recommended. The ITSP MUST support outband DTMF (RFC2833/RFC4733) if UC Suite functions via SIP trunk (e.g. auto attendant, voicemail control) shall be used.
    • inband transport may be used, but the functionality cannot be guaranteed as endpoints (e.g. UC-Suite) may not support inband DTMF.
  • FAX over IP with T.38 is recommended for analog Fax devices, terminal adapters and the OpenScape Business UC Suite.
    • If your provider does not support Fax T.38, Fax pass-through with G.711 is possible but transmission quality depends on network infrastructure in this case.
    • Since OpenScape Business V2 UC Suite is able to handle T.38 to G.711 fax fallback as well.
  • An incoming ITSP call can be transferred or forwarded to another public subscriber via ITSP. 2 lines (one incoming and one outgoing) are used while the call is active.
  • A trunk prefix to select a SIP trunk as an alternate trunk can be used from the OpenScape Business client's dial box but not from client's directories and settings (myPortal, myAttendant, myAgent).
  • Because of the above limitation SIP trunks cannot be used for presence based call forwarding if a TDM trunk is present in parallel .
  • Special call numbers and emergency calls may need alternate TDM connections
    • Special call numbers (e.g. 0800, 0900, 0137) are not supported by all SIP providers
    • analog fax/modem connections are not supported by all SIP providers.
    • Emergency call numbers (e.g. 110, 112) are not supported by all providers.

How to get a new VoIP provider released

Tests are necessary with every new provider before making installations in the field due to different implementations of the SIP protocol. Otherwise no support is available for an ITSP. Test resources have to be provided by the region or partner.

  • Select the VOIP / SIP trunking providers, which are most important for your business, estimate business relevance and get agreement for start of certification from product management.
  • Download zip.png  VOIP provider data collection and test list - NEW update: 2017-12-14
    In the .zip-file you find a process description, the testlist and a template for writing a configuration guide.

After successful tests the VoIP provider will be released and published on this page. Regular back level support is available for issues with the new provider after that. A preconfigured VoIP provider profile will be included in the OpenScape Business administration for easy setup. Certified providers are entitled to label their SIP Trunking Service with the OpenScape Business certified ITSP emblem

General Configuration guides

pdf-en.png  OSBiz V1 Configuration for ITSP- latest update: 2014-12-17

pdf-en.png  OSBiz V2 Configuration for ITSP- latest update: 2016-01-15

pdf-en.png  HowTo-CLIPnoScreeningEng- latest update: 2015-10-26

pdf-de.png  HowTo-CLIPnoScreeningDeu- latest update: 2015-11-04

Tested VoIP Providers by Countries

The main SIP trunking functions of the SME platforms have been tested with the following Internet telephony providers. For detailed information see the document Overview about Released SIP Providers below.


VoIP Providers Configuration Guide
Verizon   pdf-en.png  Verizon IP-Trunk Configuration

latest update: 2013-05-10

Skype Connect   -
  • Please check provider home page for supported countries.
  • Skype Connect is a fee-based business service from Skype. It allows voice communication between Skype clients and office phones using the standard SIP trunking interface. Other Skype client features like chat or video are currently not supported.

Skype Connect certified logo Our SME Platforms have been officially certified by Skype. pdf-en.png  Skype Connect with SME platforms


VoIP Providers Configuration Guide
BroadCloud pdf-en.png  BroadCloud Configuration

latest update: 2017-07-27

Commander Primus -
Engin -
Internode -
Telstra -


VoIP Providers Configuration Guide
IP Austria / my Tweak   -
Kabelplus Business Phone   -
LinzAG City Voice   -
Neotel   -
SalzburgAG CableLink   -
Tele2   -
UPC Austria   -


VoIP Providers Configuration Guide
Belgacom IMS / Proximus   -
BKM   -
Destiny -
Orange pdf-en.png  Orange Belgium Configuration

new: 2017-11-17

Telenet -
WIN   -


VoIP Providers Configuration Guide
Voitel -


VoIP Providers Configuration Guide
BabyTEL   -


VoIP Providers Configuration Guide

Czech Republic

VoIP Providers Configuration Guide
O2 -
T-mobile -


VoIP Providers Configuration Guide
Global Connect -
TDC pdf-en.png  TDC Denmark

latest update: 2017-02-10

Telia pdf-en.png  TeliaDenmark

latest update: 2017-04-28

Uni-tel A/S -


VoIP Providers Configuration Guide
Elisa   -
Länsilinkki -
Telia-Sonera -


VoIP Providers Configuration Guide
Acropolis Telecom   -
Bouygues -
BroadCloud pdf-en.png  BroadCloud Configuration

latest update: 2017-07-27

Completel -
Hexatel -
MyStream   -
OpenIP   -
Paritel Operateur -
Sewan Communications -


VoIP Providers Configuration Guide
1&1   -
BroadCloud pdf-en.png  BroadCloud Configuration

latest update: 2017-07-27

Deutsche Telefon pdf-de.png  Deutsche Telefon Konfiguration

latest update: 2017-07-27

ecotel sipTrunk DDI -
ecotel sipTrunk Connect 1.0 -
ecotel sipTrunk 2.0 pdf-de.png  Ecotel SipTrunk2.0 Konfiguration

latest update: 2017-03-28

ennit AG (formerly tng) -
Equada   -
GMX (now 1&1)   -
gnTel   pdf-de.png  gnTel Konfiguration

latest update: 2017-08-08

HFO   -
HL-Komm pdf-de.png  HL-Komm Konfiguration

latest update: 2017-07-27

M-Net pdf-de.png  M-net-Premium Konfiguration

NEW! latest update: 2017-10-13

MK Netzdienste   -
NFON pdf-en.png  NFON Configuration

NEW! latest update: 2017-10-13

Peoplefone AG   -
O2 All-IP Voice SIP   pdf-de.png  O2 All-IP Konfiguration

latest update: 2017-08-14

Purtel   -
QSC IPfonie extended (DID) -
QSC IPfonie extended Connect (DID) pdf-de.png  QSC IPfonie extended connect Konfiguration

latest update: 2017-12-06

sipgate basic (MSN)   -
sipgate trunking (DID)   -
Deutsche Telekom IP-As mit MSN   pdf-de.png  Deutsche Telekom DIPVD Konfiguration

latest update: 2017-07-27

Deutsche Telekom DeutschlandLAN SIP-Trunk   pdf-de.png  Deutsche Telekom SIP-Trunk Konfiguration

latest update: 2017-07-27

toplink   -
Vodafone Anlagenanschluss (formerly Arcor)   -
Vodafone Anlagenanschluss R3 (DID)   pdf-de.png  Vodafone IP-ALA-R3 Konfiguration

latest update: 2017-08-14


VoIP Providers Configuration Guide
CosMote   pdf-en.png  COSMOTE Configuration

latest update: 2016-10-02

Hong Kong

VoIP Providers Configuration Guide
Hong Kong Broadband Network pdf-en.png  HKBN Configuration

latest update: 2017-07-27


VoIP Providers Configuration Guide
BroadCloud pdf-en.png  BroadCloud Configuration

latest update: 2017-07-27

Infracom (ex Multilink)   -
Viatek -


VoIP Providers Configuration Guide
FL1 Telekom   pdf-de.png  FL1 Konfiguration

latest update: 2016-04-14


VoIP Providers Configuration Guide
Telefonica   -

The Netherlands

VoIP Providers Configuration Guide
BCOM pdf-en.png  BCOM Configuration

latest update: 2016-03-21

BLU pdf-en.png  BLU telecom Configuration

latest update: 2016-05-02

Deanconnect B.V.   -
gnTel NL   pdf-en.png  gnTel Configuration

latest update: 2017-08-08

Infopact   -
KPN VoiPConnect pdf-en.png  KPN Configuration

latest update: 2017-07-27

Motto Communications -
OneCentral   -
OneXS -
RoutIT -
SIGNET B.V.   pdf-en.png  SIGNET Configuration

latest update: 2016-09-30

Speakup   -
Tele2 -
T-Mobile NL -
Vodafone NL -
Voiceworks   -
Voiceworks MEX NDL   pdf-en.png  Voiceworks MEX Configuration

latest update: 2017-07-27

X2COM pdf-en.png  X2COM Configuration

latest update: 2016-06-03

Ziggo   -

New Zealand

VoIP Providers Configuration Guide
TelstraClear   -


VoIP Providers Configuration Guide
Portugal Telecom   -


VoIP Providers Configuration Guide
Orion Telekom   -
Telenor   -


VoIP Providers Configuration Guide
Slovak Telekom   -


VoIP Providers Configuration Guide
Amis / A1   -
Detel   -
MegaM   -
T-2   -
Telemach   -

South Africa

VoIP Providers Configuration Guide
Nashua NCN -
Vodacom -


VoIP Providers Configuration Guide
LCR (Least Cost Routing) -
Telecable -
vozelia   -
VozTelecom pdf.png  VozTelecom configuración

latest update: 2016-08-07


VoIP Providers Configuration Guide
Tele2   -
Telia   -


VoIP Providers Configuration Guide
efon -
Peoplefone AG   -
sipcall -
Sunrise pdf-de.png  Sunrise Konfiguration

latest update: 2017-01-11

Swisscom BCON -
Swisscom Smart Business Communication   -
Swisscom VoIP Gate   -
Swisscom Enterprise SIP   -
Telco Pack SA   -
vtx   -

United Kingdom

VoIP Providers Configuration Guide
BroadCloud pdf-en.png  BroadCloud Configuration

latest update: 2017-07-27

Gamma   -
KCOM   pdf-en.png  KCOM Configuration

latest update: 2016-06-03

Opal   -
TalkTalk   -
tIPicall   -
Vodafone UK pdf-en.png  Vodafone UK Configuration

latest update: 2017-11-08

Voiceflex   -
VoIP Ltd i-Line   -

United States of America

VoIP Providers Configuration Guide
AT&T pdf-en.png  AT&T Configuration

latest update 2013-09-07

BroadCloud pdf-en.png  BroadCloud US Configuration

latest update: 2017-07-27

Cbeyond   -
CenturyLink   -
Fusion 360 pdf-en.png  FusionConnect Configuration

latest update: 2017-07-27

Intermedia   -
Sotel   -

(Broadsoft platform only)

XO   -

Released SIP Providers in Detail

The table above shows the ITSPs that passed successfully a connectivity test. More details about test results, supported features and restrictions for a specific ITSP are listed in following PDF document.

pdf-en.png  Overview about Released SIP Providers Latest update: 2017-10-13

The following scenarios are covered within the connectivity test:

  • Registration
  • Basic Calls from / to ITSP
  • Feature Tests
    • Consultation, transfer, toggle, conference
    • Call Pickup / ringing group scenarios
    • call forwarding scenarios
    • DTMF
    • CLIP / CLIR
    • COLP / COLR
    • FAX
  • Special Tests
    • emergency calls
    • service calls
    • long duration calls
  • Calls handled via UC application

The connectivity tests are performed using various endpoints (for details see test list).

Frequently asked Questions

External Links