Lancom 1722 VOIP User manual

LANCOM 1722 VoIP
LANCOM 1724 VoIP

© 2006 LANCOM Systems GmbH, Wuerselen (Germany). All rights reserved.
While the information in this manual has been compiled with great care, it may not be deemed
an assurance of product characteristics. LANCOM Systems shall be liable only to the degree spec-
ified in the terms of sale and delivery.
The reproduction and distribution of the documentation and software included with this product
is subject to written permission by LANCOM Systems. We reserve the right to make any alterations
that arise as the result of technical development.
All explanations and documents for registration of the products you find in the appendix of this
documentation, if they were present at the time of printing.
Trademarks
Windows®, Windows XP®and Microsoft®are registered trademarks of Microsoft, Corp.
The LANCOM Systems logo, LCOS and the name LANCOM are registered trademarks of LANCOM
Systems GmbH. All other names mentioned may be trademarks or registered trademarks of their
respective owners.
This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit
http://www.openssl.org/.
This product includes cryptographic software written by Eric Young ([e-mail]).
This product includes software developed by the NetBSD Foundation, Inc. and its contributors.
Subject to change without notice. No liability for technical errors or omissions.
LANCOM Systems GmbH
Adenauerstr. 20/B2
52146 Wuerselen
Germany
www.lancom.de
Wuerselen, May 2006
110426/0506

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Preface
3
EN
Preface
Thank you for your confidence in us!
The LANCOM 1722 VoIP and LANCOM 1724 VoIP models offer integrated
DSL, ADSL and ISDN interfaces and a LAN switch. This router allows you to
connect a single workstation or even an entire local network to the high-
speed Internet, easily and conveniently.
Additional to its data transfer functions, the LANCOM VoIP Router is a fully
fledged, integrated VoIP communications solution. Along with Quality of
Service functions which are optimized for VoIP, the LANCOM VoIP Router
offers the full range of options required for voice communications over data
networks and the step-by-step, cost-effective and simple migration from
existing telecommunications systems to corporate VoIP.
LANCOM VoIP Router provides the comprehensive functions of an access
router, professional firewall and high-quality VPN gateway in a single, com-
pact device. It thus combines investment protection and cost savings as a reli-
able voice over IP solution for small and mid-sized enterprises, home and
branch offices.
SIP proxy for registration with providers and superordinated VoIP PBXs.
SIP gateway with transparent transition between SIP and ISDN
Intelligent call routing and number conversion
Point-to-point and point-to-mulitpoint-connection support
Multiple configurable ISDN interfaces (NT/TE)
Life-line support (LANCOM 1722 VoIP only)
Voltage relay to the internal ISDN bus for specific interfaces
Stateful-inspection firewall and VPN gateway
LANCOM products undergo continuous development. For precise
information about their features and for the latest version of the LCOS
operating system, please visit the LANCOM website.
Security settings
For a carefree use of your device, we recommend to carry out all security set-
tings (e.g. Firewall, encryption, access protection, charge lock), which are not
already activated at the time of purchase of your device. The LANconfig wizard
’Check Security Settings’ will support you accomplishing this.

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Preface
4
EN
We ask you additionally to inform you about technical developments and
actual hints to your product on our Web page www.lancom.de, and to down-
load new software versions if necessary.
User manual and reference manual
The documentation of your device consists of three parts: the installation
guide, the user manual and the reference manual.
You are now reading the user manual. It contains all information you need to
start your device. It also contains the most important technical specification
for the device.
The reference manual can be found on the CD as an Acrobat (PDF) document.
It is designed as a supplement to the user manual and goes into detail on top-
ics that apply to a variety of devices. These include for example:
Systems design of the LCOS operating system
Configuration
Management
Diagnosis
Security
Routing and WAN functions
Firewall
Quality of Service (QoS)
Virtual Private Networks (VPN)
Virtual Local Networks (VLAN)
Wireless Networks (WLAN)
Voice Communications for computer networks using voice over IP (VoIP)
Backup Solutions
LANCAPI
Further server services (DHCP, DNS, charge management)
This documentation was compiled …
...by several members of our staff from a variety of departments in order to
ensure you the best possible support when using your LANCOM product.
In case you encounter any errors, or just want to issue critics or enhance-
ments, please do not hesitate to send an email directly to: [e-mail]

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Preface
5
EN
Our online services ( www.lancom.de) are available to you around the
clock should you have any queries regarding the topics discussed in
this manual or require any further support. In addition support from
LANCOM Systems is also available to you. Telephone numbers and
contact information for LANCOM Systems support can be found on a
separate insert, or at the LANCOM Systems website.
Notes symbols
Very important instructions. If not followed, damage may result.
Important instruction that should be followed.
Additional instructions which can be helpful, but are not
required.

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Contents
6
EN
Contents
1 Introduction 10
1.1 How does ADSL and ADSL 2+ work? 10
1.2 Which use does VPN offer? 12
1.3 Firewall 13
1.4 Voice over IP 15
1.4.1 Example applications 15
1.4.2 The central position of the LANCOM VoIP Router 19
1.5 Call switching: Call routing 22
1.5.1 SIP proxy and SIP gateway 23
1.5.2 User registration at the SIP proxy 23
1.5.3 Number translation at network transitions 27
1.5.4 The Call Manager 28
1.5.5 Making telephone calls with the LANCOM VoIP Router
29
1.5.6 VoIP characteristics of the LANCOM VoIP Routers 34
1.6 What can your LANCOM Router do? 36
2 Installation 40
2.1 Package contents 40
2.2 System preconditions 40
2.3 Introducing LANCOM Router 41
2.3.1 Status displays 41
2.3.2 The back of the unit 45
2.4 Hardware installation 46
2.5 ISDN interface configuration 48
2.5.1 Bus termination, life-line support and power relay 49
2.5.2 Protocol setting 51
2.5.3 ISDN connection timing 52
2.6 Software installation 52
2.6.1 Starting LANCOM setup 53
2.6.2 Which software should you install? 53

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Contents
7
EN
3 Basic configuration 55
3.1 Which information is necessary? 55
3.1.1 TCP/IP settings 55
3.1.2 Configuration protection 57
3.1.3 Settings for the DSL connection 57
3.1.4 Settings for the ISDN connection 57
3.1.5 Connect charge protection 58
3.2 Instructions for LANconfig 58
3.3 Instructions for WEBconfig 60
3.4 TCP/IP settings to workstation PCs 63
4 Setting up Internet access 65
4.1 Instructions for LANconfig 67
4.2 Instructions for WEBconfig 67
5 Configuring Voice over IP 68
5.1 Instructions for LANconfig 68
5.2 Configuration examples 68
5.2.1 VoIP telephony for stand-alone use 69
5.2.2 Using VoIP telephony to extend the downstream ISDN
PBX 77
5.2.3 Using VoIP telephony to supplement existing ISDN tele-
phones 84
5.2.4 Connecting to an upstream SIP PBX 87
5.2.5 VoIP coupling for locations without a SIP PBX 92
5.2.6 Connection diagnosis with LANmonitor 99
6 Linking two networks 100
6.1 What information is necessary? 101
6.1.1 General information 101
6.1.2 Settings for the TCP/IP router 103
6.1.3 Settings for the IPX router 104
6.1.4 Settings for NetBIOS routing 105
6.2 Instructions for LANconfig 106
6.3 Instructions for WEBconfig 106

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Contents
8
EN
7 Providing dial-up access 108
7.1 Which information is required? 108
7.1.1 General information 109
7.1.2 Settings for TCP/IP 110
7.1.3 Settings for IPX 111
7.1.4 Settings for NetBIOS routing 111
7.2 Settings for the dial-in computer 112
7.2.1 Dial-up via VPN 112
7.2.2 Dial-up via ISDN 112
7.3 Instructions for LANconfig 113
7.4 Instructions for WEBconfig 113
8 Sending faxes with LANCAPI 115
8.1 Installation of the LANCOM LANCOM VPN 116
8.2 Installation of the MS Windows fax service 117
8.3 Sending a fax 118
8.3.1 Send a fax with any given office application 118
8.3.2 Send a fax with the MS Windows fax service 118
9 Security settings 120
9.1 The security settings wizard 120
9.1.1 Wizard for LANconfig 120
9.1.2 Wizard for WEBconfig 121
9.2 The firewall wizard 121
9.2.1 Wizard for LANconfig 121
9.2.2 Configuration under WEBconfig 122
9.3 The security checklist 122
10 Troubleshooting 126
10.1 No WAN connection is established 126
10.2 DSL data transfer is slow 126
10.3 Unwanted connections under Windows XP 127
10.4 Cable testing 127

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Contents
9
EN
11 Appendix 129
11.1 Performance data and specifications 129
11.2 Contact assignment 130
11.2.1 ADSL interface 130
11.2.2 ISDN 1 interface 130
11.2.3 ISDN 2 interface 131
11.2.4 Ethernet interfaces 10/100Base-T 131
11.2.5 Configuration interface (Outband) 132
11.3 CE declaration of conformity 132

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
10
EN
1Introduction
LANCOM 1722 VoIP are fully-featured routers that therefore also can be used
in combination with the integrated firewall for providing secure Internet
access to a complete local network (LAN).
The integrated VPN option enables the devices to act as powerful Dynamic
VPN gateways for external offices or mobile users.
The LANCOM Router models offer each a DSL or ADSL connector and also an
ISDN connectors. One ISDN line can be used as back-up for the DSL connec-
tion, for remote management of the router, as basis for the office communi-
cation via LANCAPI or for establishing VPN connections to remote sites with
dynamic IP addresses.
By using the Voice over IP function, these devices can transfer voice data over
broadband Internet connections and ISDN interfaces as well.
1.1 How does ADSL and ADSL 2+ work?
ADSL (Asymmetric Digital Subscriber Line) is currently the most common
broadband Internet connection technology. Standard and almost ubiquitous
telephone lines (analog or DSL) are the basis for DSL data transfer to the near-
est telephone exchange. From here, the data is passed directly on to the Inter-
net over high-speed connections.
The asymmetric ADSL version of DSL was designed for applications in which
the user receives high volumes of data but only transmits relatively small vol-
umes, e.g. for accessing the world wide web (www). With an ADSL connec-
tion, a user can download at up to 8 Mbps (“downstream”) and upload at up
to 800 Kbps (“upstream”). These maximum rates can be reduced as required
by the ADSL provider.
To satisfy the strongly increasing demand for higher bandwidths, the stand-
ards ADSL 2 and ADSL 2+ provider higher data rates as a basis for applica-
tions such as video streaming or high-definition TV (HDTV) over the Internet.
Depending on the Internet provider, ADSL 2 devices support data rates of up
to 12 Mbps, and ADSL 2+ devices support up to 24 Mbps. Handshake rou-
tines during connection establishment ensure that the standards ADSL,
ADSL 2 and ADSL 2+ are intercompatible.
With ADSL, all traditional telephony applications (telephone, fax, answering
machine, PBX) can still be used without restrictions. So-called splitters make
this possible. Splitters are devices that separate the telephone line's “voice

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
11
EN
frequencies” from the “data frequencies” and ensure that the signals are for-
warded to the appropriate networks.
A splitter is also used at the subscriber end to permit ADSL modems/routers
and conventional telephone equipment to be used at the same time. The
router is connected to a seperate ADSL modem, the ADSL modem is connected
to the splitter.
In the LANCOM 1722 VoIP the ADSL/ADSL 2+ modem is integrated directly in
the device. It can be directly connected to the splitter with the supplied cable.
ADSL can operate over modern ISDN telephone service as well as conven-
tional analog service (POTS – Plain Old Telephone Service). Devices with inte-
grated ADSL modem are offered in two different versions. You can determine
which telephone system a device supports by looking at the model description
on the bottom of the device. The label containing the device name also con-
Power LAN WLAN
-1 WLAN -2 WAN Message
Internet
Splitter
LANCOM VoIP Router
Telephone
Telephone
network
Splitter
ADSL provider
Switching node
DSLAM Subscriber
ADSL
modem
Router with integrated
ADSL modem
Internet
Splitter
Telephone
Telephone
network
Splitter
ADSL provider
Switching node
DSL access
multiplexer
Subscriber

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
12
EN
tains an additional code which stands for the telephone system the device
supports:
An 'Annex A' type LANCOM Router can only be used with ADSL-over-POTS
service. Similarly, an 'Annex B' device can only be used with ADSL-over-ISDN
service. Your network operator will be able to inform you of the version you
need. Retrofitting a device to function with a different telephone system is not
possible.
ADSL-over-ISDN connections also exist that do not operate in conjunction
with ISDN, but which use a conventional analog telephone connection. A
prominent example would be Deutsche Telekom’s T-DSL service.
1.2 Which use does VPN offer?
A VPN (Virtual Private Network) can be used to set up secure IP networks via
Internet.
The following structure results when using the Internet instead of direct con-
nections :
Code Supported telephone system
'Annex A' ADSL-over-POTS
'Annex B' ADSL-over-ISDN



Head Office
Workstation in remote
access
Internet
LAN
LAN
Subsidiary

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
13
EN
All participants have fixed or dial-up connections to the Internet. Expensive
dedicated lines are no longer needed.
All that is required is the Internet connection of the LAN in the headquar-
ters. Special switching devices or routers for dedicated lines to individual
participants are superfluous.
The subsidiary also has its own connection to the Internet.
The RAS PCs connect to the headquarters LAN via the Internet.
The Internet is available virtually everywhere and typically has low access
costs. Significant savings can thus be achieved in relation to switched or ded-
icated connections, especially over long distances.
The physical connection no longer exists directly between two participants;
instead, the participants rely on their connection to the Internet. The access
technology used is not relevant in this case: ideally is the use of broadband
technologies such as DSL (Digital Subscriber Line). But also a conventional
ISDN line can be used.
The technologies of the individual participants do not have to be compatible
to one another, as would be the case for conventional direct connections. A
single Internet access can be used to establish multiple simultaneous logical
connections to a variety of remote stations.
The resulting savings and high flexibility makes the Internet (or any other IP
network) an outstanding backbone for a corporate network.
1.3 Firewall
The integrated Stateful Inspection Firewall ensures an effective protection
against undesired intrusion in your network by permitting only incoming data
traffic as reaction to outgoing data traffic. The router’s IP masquerading func-
tion hides all workstations of the LAN behind a single public IP address. The
actual identities (IP addresses) of the individual workstations remain con-
cealed. Firewall filters of the router permit specific IP addresses, protocols and
ports to be blocked. With MAC address filters it is also possible to specifically

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
14
EN
monitor the access of workstations in the LAN to the IP routing function of the
device.
Further important features of the Firewall are
Intrusion Detection
Break-in attempts into the local network or on the central Firewall are rec-
ognized, repelled and logged by the Intrusion Detection system (IDS) of
the LANCOM DSL. Thereby it can be selected between logging within the
device, email notification, SNMP trap or SYSLOG alarms.
Denial-of-Service Protection
Attacks from the Internet can be break- in attempts as well as attacks with
the aim of blocking the accessibility and functionality of individual
services. Therefore a LANCOM DSL is equipped with appropriate protec-
tive mechanisms, which recognize well-known hacker attacks and which
guarantee the functionality.
Quality-of-Service / Traffic management
The generic term Quality-of-Service (brief: QoS) summarizes the functions
of the LANCOM which guarantee certain service qualities. The advantage
is that the QoS functions can take place by means of the existing powerful
classification methods of the Firewall (e.g. limitation of subnetworks,
single workstations or certain services).
Guaranteed minimum bandwidths give priority to enterprise critical appli-
cations, VoIP PBX installations or certain user groups.
More details about the function of the Stateful Inspection Firewall of
your LANCOM Router can be found in the reference manual on the
LANCOM CD.
Firewall
Internet
LAN
LANCOM

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
15
EN
1.4 Voice over IP
The term Voice over IP (VoIP) refers to voice communications over computer
networks based on the Internet protocol (IP). The core idea is to provide the
functions of traditional telephony via cost-effective and wide-spread net-
working structures such as the Internet. VoIP itself is not a standard, rather it
is a collective term for the various technologies (equipment, protocols, voice
encoding, etc.) which make voice communications in IP networks possible.
1.4.1 Example applications
Voice over IP solutions offers advantages across a broad spectrum of applica-
tions, starting with small companies and extending to large corporations with
extensive networks of subsidiaries. In the following section, we will demon-
strate a number of examples.
Detailed information about configuration is available in the chapter
'Configuration of VoIP functions' or in the LCOS reference manual.
Supplementing existing ISDN PBXs
VoIP functions can be conveniently added in to existing telephone structures
by using a LANCOM VoIP Router. The LANCOM VoIP Router is simply con-
nected between the public ISDN connection (e.g. ISDN NTBA) and the ISDN
PBX.
ISDN PBX
LANCOM VoIP Router
between NTBA and
PBX
Internet
ISDN
ISDN telephones
VoIP telephoneVoIP softphone
ISDN network
subscribers
Public SIP provider
ISDN NTBA
Analog fax
machines and
telephones

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
16
EN
Telephone calls over the PBX and its ISDN telephones remain possible just as
before; the telephones remain available under the familiar telephone num-
bers. This application additionally offers the following options:
In addition to the ISDN telephones, VoIP telephones or VoIP softphones
can be included in the telephone infrastructure. VoIP subscribers in the
internal LAN are also able to call external ISDN subscribers.
The ISDN telephones continue to function, and additionally they can call
all of the internal VoIP telephones and softphones in the LAN.
Calls to external SIP subscribers who use the same Internet provider are
often available at no cost.
With the appropriate connection to a public SIP provider, any other SIP
subscriber worldwide can be called, irrespective of the provider network.
As an alternative to a direct ISDN connection, ISDN network subscribers
can also be reached over a diversion via the SIP provider. The costs depend
on the provider's particular tariff models. Frequently, long-distance and
overseas calls via a SIP provider are significantly cheaper than the tradi-
tional telephone connection.
In this constellation, the LANCOM VoIP Router takes over the switching of the
calls. The device can be individually configured, for example, to use the access
codes to decide upon the switching of a call either via the ISDN interface, or
via the Internet as a VoIP call.
Connecting subsidiaries or home offices to the headquarters
Many subsidiaries or home offices already have a connection to the network
at headquarters over VPN. These connections are normally limited to conven-
tional data transmission. By using VoIP, internal company calls can be made
for free over the existing VPN connection and—thanks to the VPN encryp-
tion—these calls are secured against eavesdropping.
With a LANCOM VoIP Router located in the branch or home office, the two
worlds of traditional and VoIP telephony can be united in a single telephone:
A VoIP telephone or an existing ISDN telephone can be used for free tele-
phone calls via VPN to the headquarters, or to make standard calls via ISDN.

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
17
EN
The advantages of a telephone connection to headquarters:
The configuration of telephone functions can be carried out centrally in
the VoIP PBX at headquarters.
Subscribers at their branch or home offices connect with the central PBX.
Calls within the company network are free.
Outgoing calls are automatically directed to the optimal line for cost opti-
mization.
VoIP for companies through SIP trunking
One of the biggest hurdles for companies that fully migrate to VoIP is to main-
tain the existing telephone numbers. Normal provider SIP accounts come with
a telephone number for the transition to the landline telephone network, but
generally these numbers are selected from a pool of numbers available to the
provider. However, for companies with a large number of telephone subscrib-
ers and numbers, it is of decisive importance that existing telephone and
extension numbers are maintained after migrating to VoIP.
With the SIP trunking function, entire ranges of telephone numbers made up
of external numbers and their associated extensions can be mapped by
LANCOM VoIP Routers over a single connection to a SIP provider, assuming
that the provider also supports Direct Dialing In (DDI) and can provide multi-
ple connections simultaneously. Generally speaking, SIP providers that offer
SIP trunking can acquire the existing telephone numbers from the former tel-
ecomms provider.
LANCOM VoIP Router Internet
ISDN
VoIP telephone
VoIP PBX connected to the
ISDN network
VPN tunnel
VoIP telephones
LANCOM
ISDN telephone
Branch office Headquarters

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
18
EN
Connecting local ISDN lines with a remote SIP gateway
Companies with nation-wide and internationally distributed sites are often
interconnected with VPN already. A LANCOM VoIP Router can be used not
only to connect the SIP and ISDN telephones at a branch office to the SIP-PBX
at headquarters; it can also integrate local ISDN networks into corporate com-
munications with help of the "SIP Gateway" function.
The SIP gateway is active for outgoing and incoming calls.
A company headquarters in New York can, for example, use a LANCOM
VoIP Router with SIP gateway located at the Los Angeles branch office to
telephone with customers and suppliers located in Los Angeles at local
rates ("local break-out").
For improved availability to customers located abroad, the New York
headquarters can, for example, use a LANCOM VoIP Router with SIP gate-
way located at their sales office in Italy. Customers can then reach support
or service numbers via a standard national telephone number. Calls from
the local ISDN network are received and directed within the company net-
work to the responsible employee. Call routing can be used which identi-
fies the customer's calling number and automatically selects the
appropriate connection to be used for forwarding the call.
Advantages of the SIP gateway:
The local ISDN connection at any site is available for use by any of the
offices throughout the entire company.
National and international long-distance calls can be mapped to local or
regional calls, so saving costs.
LANCOM VoIP
Router Internet
Local ISDN network
VoIP PBX
VPN tunnel
VoIP telephones
LANCOM
Branch office Headquarters

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
19
EN
Automatic routing of incoming calls to the responsible employee.
Connecting sites without a SIP PBX
Companies with widely disperse offices and without their own SIP PBX can
also take advantage of VoIP site coupling. In this "peer-to-peer" scenario, two
sites are equipped with LANCOM VoIP Router.
Along with data transfer via VPN, it is also possible to use VoIP functions
between the two locations.
The advantages of peer-to-peer site coupling
ISDN PBXs at different locations can form a common internal telephone
network.
An SIP PBX is not necessary.
Calls within the company network are at no charge.
Outgoing calls are automatically directed to the optimal line for cost opti-
mization.
Incoming calls can be switched directly to the appropriate employee at a
different location.
1.4.2 The central position of the LANCOM VoIP Router
LANCOM VoIP Router take up a central position in the switching of telephone
calls between internal and external subscribers over the different channels of
communication. Depending on the model and equipment, the devices inter-
connect the following communication participants and channels into a com-
mon telephone infrastructure.
LANCOM VoIP Router
Internet
ISDN
VoIP subscribers
VPN tunnel
VoIP subscribers
LANCOM VoIP Router
ISDN PBX
ISDN telephones
Analog fax
machines and
telephones
ISDN PBX

LANCOM 1722 VoIP – LANCOM 1724 VoIP
Chapter 1: Introduction
20
EN
Internal VoIP terminal devices connected to LAN, WLAN and DMZ, such
as SIP telephones and SIP softphones
The internal ISDN infrastructure with ISDN PBX and ISDN telephones
Analog terminal devices, internally connected either into the ISDN net-
work via a PBX with a/b ports, or alternatively into the VoIP network over
an ATA (Analog Telephone Adapter).
External SIP providers and all of the external subscribers attainable via
them
Upstream SIP PBXs with all of the internal and external subscribers attain-
able through it
The external ISDN world via ISDN NTBA or upstream ISDN PBX, and all of
the external subscribers available via the land-line network
Users and lines
Telephony subscribers in internal areas can take part in voice communications
and, in the LANCOM VoIP environment, are referred to as "users". The
LANCOM differentiates between:
ISDN users
S
I
P
u
s
e
r
S
I
P
p
r
o
v
i
d
e
r
S
I
P
P
B
X
I
S
D
N
n
e
t
w
o
r
k
u
s
e
r
s
I
S
D
N
a
n
a
l
o
g
e
u
s
e
r
s





