One of the things that many clients want with any deployment is the option for at least a few wireless handsets. Whilst it could be argued that Lync 2013 offers a range of options when it comes to supporting a wireless client over Wi-Fi or 3/4G, it’s not always the magic bullet we would all like it to be. Internal Wi-Fi networks can sometimes be less than ideal, particularly when attempting to support real time communications, and it’s still common to come across 3/4G black spots, particularly when inside a building or in regional areas. There is of course another technology option if we would like to support medium range wireless telephony within our Lync deployments: DECT

We’re all familiar with DECT, or Digital Enhanced Cordless Communications. It’s the same technology we’ve had in our homes for years, and is utilised today by a range of Lync certified wireless headsets (some examples can be found over at Plantronics and Jabra). What’s been missing is a native Lync DECT handset solution.

We can all be thankful then that Spectralink have a range of handsets that have been tested and qualified for use with Microsoft Lync 2010 and 2013, in both WiFi and DECT models. This article focuses on Spectralink’s DECT offering, providing integrators with a DECT wireless option when deploying Enterprise Voice for their customers.

The Handsets

There are a range of DECT handsets to choose from, each targeting a specific vertical:

Model	Use
Butterfly Series	Light use office environments
77 Series	Healthcare
76 Series	Manufacturing
75 Series	Mobile worker/administration environments
74 Series	Harsh environments (oil, gas)

The Spectralink 7000 Site Survey handset is also available, which looks to be a handy tool for integrators deploying Spectralink DECT networks. Looking forward to trialling this in the future.

The Infrastructure

The DECT handsets subscribe to an IP-DECT server, which in turn communicates with the Lync environment. The system could consist of a single IP-DECT server and a few handsets, right through to a network of IP-DECT servers, base stations and repeaters that support hundreds of handsets.

IP-DECT Servers

There are two flavours of IP-DECT server:

Model	Use
IP-DECT Server 400	SMB, 30 wireless users, 12 voice channels
IP-DECT Server 6500	Larger organisations, modular, supports up to 4,096 wireless users

Note that the number of channels supported by each server version is reduced when Secure RTP (SRTP) is enabled between the Spectralink servers and Lync.

DECT Base Station/Repeater

The IP-DECT base stations are controlled by the IP-DECT server, providing a link between the handset and the IP-DECT server. The DECT repeater can be used to extend the coverage of the DECT servers/base stations.

Model	Use
IP-DECT Base Station	Over the air call signaling between the IP-DECT server and handsets
DECT Repeater	Building block that extends the DECT coverage area

For smaller deployments, the IP-DECT Server 400 combines the role of server and base station into a single unit. For larger deployments, the IP-DECT server requires the deployment of at least one IP-DECT Base Station. Both servers support the deployment of DECT repeaters, however these are not a required component:

The Configuration

Guides

I’ve referred to the following guides when configuring integration between Spectralink and Microsoft Lync Server 2013:

Spectralink IP-DECT Server 400 Installation and Configuration Guide

Spectralink IP-DECT Server 400 and 6500 and Microsoft Lync Server Configuration Guide

Prerequisite Configuration

DNS

• Choose a FQDN for your Spectralink server, and add it to DNS. In this example, I’m using DMU-DECT400.dmunified.com

  

   

Lync Configuration

There are two methods that we can use to register a user to Lync: System Authentication (Trusted Server) or User Authentication (NTLM):

• Trusted Server method – When configured this way, the Spectralink 400 server is setup as a trusted application server within the Lync environment. When configuring user accounts from the Spectralink Web GUI, only the SIP prefix (e.g. Damien.Margaritis) needs to be specified. It’s also possible to change the SIP prefix from the handset instead of the Web GUI, something you can’t do when using NTLM authentication (there’s no way to enter AD credentials from the handset).
• NTLM method – When configured for NTLM authentication, the Spectralink 400 server is not added as a trusted application server to the Lync environment. Because of this, each user that’s configured via the Spectralink Web GUI will require AD username and password details to support NTLM authentication.

In this blog article, we’re going to configure the Spectralink server as a trusted application server from the Lync Management Shell (this is Spectralink’s recommended method)

Configure Trusted Application Server

From the Lync Management Shell:

• If you don’t know your Lync Site ID, run Get-CsSite first and note it down

• Run New-CsTrustedApplicationPool -Identity DMU-DECT400.dmunified.com -Site DMUNIFIED -RequiresReplication $false -ThrottleAsServer $true -TreatAsAuthenticated $true -Registrar lyncpool01.dmunified.com
• Click Y when presented with the topology publishing warning (this is expected). You should see something similar to this:

• Run New-CsTrustedApplication -ApplicationId DECT -Port 5061 -TrustedApplicationPoolFqdn DMU-DECT400.dmunified.com

• Run Enable-CsTopology

Spectralink 400 Server Configuration

General Configuration

• From the Web GUI, open Configuration > General, and configure the following settings:
  • IPv4
  • DNS
  • NTP

Firmware Version

Make sure your firmware version is up to date (at time of writing, latest version was PCS14, download here.

• From the Web GUI, open Status > General. Confirm the PCS version is current

 Licensing

To support integration with Lync, a license is required. Make sure this is applied:

• From the Web GUI, open Administration > License

• Copy the License key into the License field, and click Load

  

• Reboot the server. You should now see the Lync license applied:

Enable Lync Support

• Open the Web GUI to Configuration > Lync, and select both options, and click Save

Certificates

So that media communication is secured between endpoints, you’ll need to import your Internal CA Root Certificate and Create/Import a host certificate.

Import Root CA certificate

To obtain the root certificate from your internal CA:

• Open a web browser to your internal CA (for example, mine’s http://dmu-dc01.dmunified.com/certsrv)
• Select Download a CA Certificate, certificate chain, or CRL

• Ensure Base 64 is selected, and click on Download CA Certificate

  

• Back on the Spectralink 400 server, open Configuration > Certificates
• Under CA Certificates, browse to the root CA you exported above, and select Import List. This will replace the default list with your internal root certificate

 

Create/Import Host Certificate

From your Lync Front End server, open IIS, and select Server Certificates

 

• From the menu on the left, click on Create Domain Certificate…
• For the common name, ensure you enter in the FQDN of the Spectralink server that you entered into DNS earlier. Fill in the rest of the details, and complete the wizard

• Right click the new certificate, and click on Export

• Choose a file location to export to, set a password and click OK

• Import the Host Certificate onto the Spectralink Server. From the Web GUI, open Configuration > Certificates
• From the Host Certificate Chain section, browse to the certificate file location, enter in the password and ensure you select PKCS#12

 

• Click on Import Certificate

• Reboot the server

SIP Server Settings

• From the Web GUI, open Configuration > SIP
• Configure the following settings:

Configuration Element	Value
Transport	TLS
DNS Record	A records
Default Domain	dmunified.com
GRUU	Selected
Use SIPS URI	Unselected
Proxies	1: sip:dmu-sba01.dmunified.com2: sip:lyncpool01.dmunified.com 3: sip:lyncpool02.dmunified.com
Ignore SDP Version	Selected
Enable media encryption (SRTP)	Selected
Require media encryption (SRTP)	Selected
Include lifetime in SDES offers	Selected
Include MKI in SDES offers	Selected

 Note: In my lab, I have two Front End pools and an SBA. A single entry for proxies is fine.

• Save and Reboot

Configure Lync User/Handset Registration

At this point, if you try to register the handset against the Spectralink server, it will fail:

For this to work, you first need to enter in the phones IPEI number from the Spectralink Web GUI, along with the Lync user’s SIP prefix.

• From the Spectralink handset, go to Menu > Settings > Status > General Information, and note down the IPEI Number

  

   

• Open the Spectralink Web GUI to Users

• Click on New
• Enter in the IPEI number of the handset, the standby text you want displayed for the user (optional), and the users SIP prefix in the Username/Extension field

  

     

• You should now have a successful registration against the Lync server

• From the Spectralink DECT handset, go to Menu > Settings > Advanced > Login > Create Login

• Select the Spectralink ARI number you want to register against (can be found on the base of the server or from the user list Web GUI). On the next page, click ok. You should now be connected:

 

From the Spectralink Web GUI, you should now have two ticks: one for Subscription from the DECT handset to the Spectralink server and one for the successful registration against the Lync server

 

Test Call

Now that we’ve completed the configuration, you should have no issue getting a call inbound/outbound from the DECT handset:

Known Limitations

For a list of known limitations when using the DECT handsets in a Lync environment, refer to Chapter 8 of the Spectralink IP-DECT Server 400 and 6500 and Microsoft Lync Server Configuration Guide. The limitation I found to be the most annoying when testing various call flows is the lack of Response Group call information for incoming Response Group calls (only the calling number is displayed).

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I hope you have found this blog post useful. If you would like to know more about Lync and Spectralink, would like a demo or would like to talk more about a solution that’s right for you, feel free to get in touch: damien.margaritis@insynctechnology.com.au.