Small branch offices in other countries and SIP Trunking RRS feed

  • General discussion

  • Hi,

    (Posting here as it is probably more to do with Enterprise Voice than just Conferencing)

    Our main company presence is in Australia, but we also have small branch offices (1-5 people) in the US and UK.  We are running Lync 2010 RC.

    I am wondering what options are available for our PSTN conferencing with local dial in numbers for the US and UK.

    Would I use a SIP Trunk from a provider in those regions that connects back to my mediation server in AUS?


    Many thanks



    Thursday, October 7, 2010 1:36 AM

All replies

  • It would depend what your requirements are for those branch offices. However if you only require centralised conferencing facilities a SIP trunk at each location will probably be your cheapest option. Most providers supply SIP trunks in multiple countries terminated back to a central site, there maybe some legal paper work to be done with some countries check with your prefered supplier.

    Chris Clark - | MCTS:OCS & UC Voice Specialization | MCSE | MCSA | CCNA http://www.unitycomms.com
    Thursday, October 7, 2010 8:21 AM
  • I've been meaning to try the following - looks like you might beat me to it.

    The US and the UK both offer free PSTN dialable SIP accounts.  You sign up, get an account & connect your Mediation server.

    Check out an up-to-date list of free accounts here.  Some are incoming calls only, but that works for what you are trying to do.



    Or try this in the US.  This service is used a lot by the Asterisk community and has proven to be reliable.




    It might work with the Mediation server, it might not - but I figured it was worth trying.  I've got a Asterisk server as a gateway out for Lync, so if the Mediation server cannot connect directly, it can connect via Asterisk.

    If you try this out, I would really like to hear how it goes.


    Paul Adams

    Thursday, October 7, 2010 7:25 PM
  • Don't forget most SIP providers only provide SIP UDP and direct OCS SIP trunks need to be SIP TCP. Also OCS doesn't have a method to logon to most of the free SIP providers so one of the reasons to use a Microsoft approved SIP provider.
    Chris Clark - | MCTS:OCS & UC Voice Specialization | MCSE | MCSA | CCNA http://www.unitycomms.com
    Thursday, October 7, 2010 7:47 PM
  • Thanks Chris and Paul for the info and replies.

    As Chris mentioned, the issue I am running into is that when adding a PSTN Gateway in Lync there is no way to give it a username and password.

    I will look around for the list of officially supported providers from Microsoft.

    If there are any other ideas, please post them.


    Thanks all.



    Thursday, October 7, 2010 11:44 PM
  • I believe you can use a SIP gateway device to put the SIP account details into and then have that register with the SIP provider, you can then setup that device as a PSTN gateway in Lync, much like the previous poster suggested doing using Asterisk.

    It means a bit of dial plan config on the SIP gateway too but should work.


    Friday, October 8, 2010 1:55 PM
  • Yes - I posted quickly without thinking too much and forgot about the TCP only issue.  Some of them might support TCP, I'll have to get round to testing and post back.  One less device in the mix is always best.

    Is it a business level professional solution?  Probably not, but it might do in a pinch when you need to organise a Conference.

    Out of interest - the MediaCodes gateway seems a good unit.  Can it support multiple SIP trucks feeding to one PBX, (Lync)?  I believe it also supports Fax detection and music on hold.  I find Asterisk a good choice but people don't like the 'hands on' approach and the learning curve.  It would be good to find a single, easy 'appliance' alternative.


    Paul Adams


    Friday, October 8, 2010 4:38 PM
  • I assume you mean Audiocodes Mediant gateway? I have not tried multiple external SIP trunks but there should be no issue you build your rules to route the calls as appropriate in the gateway. Most gateways support fax detection and music on hold. Asterisk is fine for a lab but not really appropriate in most commercial implementations as it is not approved. A list  of the approved gateways, PBX's and SIP trunk providers can be found here http://technet.microsoft.com/en-us/office/ocs/bb735838.aspx
    Chris Clark - | MCTS:OCS & UC Voice Specialization | MCSE | MCSA | CCNA http://www.unitycomms.com
    Friday, October 8, 2010 6:01 PM
  • If you do provide a sip trunk link at your branch office, most likely you will be hooking it to an SBA/gateway appliance of some sort.  Just note that when users at the branch site are conferencing, since they dont have a full scaled frontend server at the branch site....they will be conferencing over the WAN.  I say this because if you offer a dialin number via the SIP trunk say from your US site....when customers call into this published US branch site number to join that conference call they will be dialing into your branch site SBA and then streaming across the WAN to the frontend server for the conference call.

    Something to think about since branch sites can tend to have smaller WAN connections.

    As the other guys have mentioned already, try to get another sip trunk line connected to the main site that supports UK and US numbers.


    Monday, April 23, 2012 4:23 PM