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Tom Arbuthnot MCSM Communications

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Setting Up DHCP Server Options Manually for Lync 2010/2013 Phones

Published 02/02/2013 - 20 Comments

Lync Phone Edition requires a number of DHCP options to allow the phones to “find their way home” to the pool and sign in. The setup is the same for 2010 and 2013.

The Options required are:

  • Option 42: NTP Server
  • Option 43: Certificate Service Provisioning URL
  • Option 120: SIP Server


These can be worked out and setup on a DHCP server via an exe and a .bat file Tom Pacyk has a good post on the automatic deployment route here and Jeff Schertz has lots of detail on the options here

The bat file route works great, but often you’ll find Admins understandably nervous when you hand then an .exe .bat to run on their DHCP server (and the exe relies on Visual C++ Redistributable) , but fear not, you can setup all the options manually.

I’m doing this for Lync 2013 with Server 2012, but the steps for Lync 2010 and 2003/2008/R2 DHCP servers are similar.


DHCPUtil is at C:\Program Files\Common Files\Microsoft Lync Server 2013


The following command will generate the input values we need

DHCPUtil.exe -SipServer –WebServer



Scope before Options are set



First We’ll point to an NTP Server

Server Options/Configure Options



NTP Server added



The other options require
• Option 43: Certificate Service Provisioning URL
• Option 120: SIP Server

First we define a new vendor class.


Click Add and type the following, you need to Type the ASCII part, that will generate the Binary. Check your numbers match for typo’s.





















We can see all these options in place


Back in Predefined Options, Choose DHCP Standard Options, Add…




Server Options/ Configure Options



Tick each option and add the info generated in DHCPUtil


Note if you make a typo you have to delete the whole field and retype it, you can’t edit “mid string”. Also watch out for the initial “.” that starts the ASCII string, you ‘ll need to delete that.






And Under Server Options, DHCP Standard Options, choose 120 UCSipServer and



Time Server


DNs Search List


Jeff also recommends adding the 004 Time Server value (and be sure to enter your time server in DNS records as per the article)



You should have the following server options


and scope options



You can test if your DHCP config is correct from a machine that would hit that DHCP server and DHCPUtil.exe -emulateclient

It will send a broadcast out


and should get a response with the options and success



Test-CsPhoneBootStrap is also a useful test


If you are hitting any issues double check your input for typo’s, it’s really easy to have an single character error, or even “.” that will stop the options working

Tom Arbuthnot

Tom Arbuthnot

Principal Solutions Architect at Modality Systems
Tom Arbuthnot is Principal Solutions Architect at Unified Communications specialist Modality Systems. He is a Microsoft Certified Master and MVP, blogger, regular on The UC Architects Podcast, and speaker at events including Microsoft TechEd and Ignite. He co-runs The Microsoft UC User Group London.


VCS - 04/02/2013 Reply

Thanks for the excellent write-up. But one question, how would you add two pools/front-end servers to the SipServer value? A customer was asking for this the other day and I cannot find any references on how to do this anywhere. I have tried comma delimiting the server names but that doesn’t seem to work. Any suggestions?

Selahattin - 06/02/2013 Reply

Hi there,

As you mentioned I have applied one by one all of the these instructions , but when running DHCPUtil.exe -emulateclient command from any other machine then I am getting the following error. I can be able to access correctly to the “” from anywhere.

DHCP Vendor Info(43) = (Length:5) UNAP(DC034E4150)

Result : Failed 1.

Kind Regards,

    Tom Arbuthnot - 10/02/2013 Reply

    Did you do this manually or by the script?

    check for typos?

      Selahattin - 11/02/2013 Reply


      I solved my issue by using the command-line below.

      set-CsRegistrarConfiguration -EnableDHCPServer $true

      Thanks and regards,

james jiang - 22/07/2013 Reply

Hi Tom,

This is really useful for us, but we are having problems when trying to deploy Lync phone (CX600) into voice vlan, it works when the data and voice in the same vlan, but not working on separated vlan, do they have different to setup vlans?

like I want:
data in vlan 10:
lync phone in vlan 11:

where I can setup vlan-id for the phones?


Note from the field: When Migration LFE DHCP Options from Lync 2010 to 2013 | LegendaryTechy Blog - 05/08/2013 Reply

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Ken Barnett - 16/09/2013 Reply

you can also try using option 43 option 10 (0A) ie in your case 0a02000b.
where 0a is the option 02=1/2 of # of bytes and 000b = 11.

kumar - 14/11/2013 Reply


I have started the Lync 2010- polycom cx3000 configuration and also i followed the steps from and from

But still i am getting error “certificate web service cannot be found pls contact your support team ” after scratched my head .

Let me explain the scenario , before going to blast with production environment me and my customer decided to test with lab environment . so we created the test vlan in dhcp server . we enabled the dhcp options as suggested by jeff blog in test VLAN .

But dns records like ( , , not yet created why because dns server is in production environment. Still time also not synchronizing , and time is showing wrong when i have checked with the device system information .

Also i updated latest ucupdates.exe in the lync control panel . But device was not getting update.

Please anyone help me , thanks in advance.

    kumar - 14/11/2013 Reply

    I unable to access the polycom cx3000 through web interface also….to do the manual change

Lync Phone Edition cannot sign in | olahl - 03/06/2014 Reply

[…] konfigurálása el?tt a hivatalos MS Technet leírások mellett átnéztem Tom Arbuthnot – Setting Up DHCP Server Options Manually for Lync 2010/2013 Phones és Jeff Schertz – Configuring Lync Server for Phone Edition Devices bejegyzéseit. Minden […]

Jan - 06/07/2015 Reply

thank you very much for this article. Adding out settings worked very well, I needed this for setting up a DHCP failover with two Windows Server 2012 R2.
Cheers from Germany

Roger - 27/07/2015 Reply

Having the same Issue with kumar, in production. Few of the phone are okay but I get error certificate web service cannot be found. Please contact your support. DHCP Server Options has been updated Manually for Lync /2013 Phones as some phones don’t have the issue. Phones are on the same VLAN, same phone version and portfast enable on port.

Rick - 11/08/2015 Reply

Very helpful in resolving a cert. issue I was having with my CX3000s.

Vijay - 17/03/2017 Reply

Hi could you please confirm these option will work for skype for business 2015?? Or its only for Lync 2010 and 2013.

    Tom Arbuthnot - 19/03/2017 Reply

    These DHCP options are for IP phones to sign in, they are the same through Lync 2010, 2013 and SfB Server, so should work fine with SfB Server 2015



Thom Voss - 23/03/2017 Reply

I have successfully ran the script, in fact many times… The issue that I experience is my DHCP resets the settings after a random amount of days which causes the phones to logout. I thought that it was related to reboots after patching but it is not that. Any suggestions?

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