PSTN Gateway Providers for OCS 2007 RRS feed

  • Question

  • Hello!

    In the past, I have set up Asterisk to utilize an external PSTN gateway, such as the ones at Vitelity.  I am now setting up OCS2007, and have run into the frustrating fact that OCS uses SIP over TCP (port 5060) to send calls via the Mediation Server to an external PSTN gateway.  I am now forced to find a new PSTN gateway provider.

    I've searched extensively and have had trouble finding any providers that state that they do in fact support OCS.  What I'd like is a company I can sign up with, port my numbers to, and then point my Mediation Server to for inbound and outbound calls.

    Can anyone recommend such a provider?

    Thank you!

    Sunday, December 30, 2007 12:02 AM

All replies

  • Essentially what you're looking for is IP trunking - available from Verizon but they do not yet support OCS.



    Wednesday, January 2, 2008 1:22 AM

    Hi Nolan,


    If your looking for a PSTN to SIP gateway I would recommend www.audiocodes.com




    Wednesday, January 2, 2008 9:00 PM
  • I think what he was looking for is a service provider, not hardware.  AKA - pointing the mediation server (or even OCS itself) at an external (internet) IP.



    Wednesday, January 2, 2008 9:43 PM
  • Hi,


    I had to write my own b2bua (a sip proxy that bridges audio) for this.  As far as I know there are no providers that speak TCP and understand REFER for supervised transfers.  If you don't do any transfers, Interactive SIP proxy is a good option, since it handles the TCP->UDP->TCP conversion.


    I'm sending outbound calls to Gafachi and iCall.  Gafachi is the most reliable one I know of, and I think several other providers are just Gafachi re-sellers.





    Wednesday, January 2, 2008 9:54 PM
  • I managed to find a provider that claims to support SIP via TCP, but we're still having some issues.  For example, calls get placed but then closed after 5 seconds because my mediation server doesn't send a SIP ACK.  The receiver of the call can't hear the person placing the call.

    I am struggling with the configuration of OCS as a whole, I think as well.  I'll be posting about that in a different part of the forum.

    Would you be willing to share your b2bua and your configuration information?

    Wednesday, January 2, 2008 11:14 PM
  • Welcome to the joy of VOIP.  Those hardware boards and T1 lines seem really expensive at first but they become more and more tempting as you deal with these kinds of issues.  Nobody implements SIP or RTP the same way. 


    Which provider did you try?


    The b2bua was a major effort, and has lots of hacks to deal with the odd things that MSS, gateways, softphones and sipphones do.  I put out feelers a while back to see if anyone was interested in a commercial version of my server, but I didn't get much interest.  I'm so busy that I wasn't able to support the few people who did try it as well as I would have liked.  I also need to improve it.  If you think OCS configuration is bad you should see the config file for this thing!


    I'm not sure why MSFT won't do this themselves.  I mean, for my little shop, it was a ton of work, but for them it would be a drop in the bucket.  I guess I can understand their insistence that TCP is the better protocol, and their hope that gateway services will implement changes, but I don't see that the providers have any real incentive to change.  


    For a product that is based around SIP phone calls, it's awfully hard to make a SIP phone call with MSS!  (I'm only talking about the Speech Server part of OCS, I don't know much about all the other bits).


    Of course, we have to temper criticism by admitting we don't have many options.  How many complete speech platforms are there? It's obviously a hard problem.



    Thursday, January 3, 2008 12:18 AM
  • http://www.interouteone.com

    set up in minutes!


    Friday, January 11, 2008 3:24 AM
  • Worked a treat for me, can't believe in and outbound telephony could be so easy to setup and use. And no need to speak to slimy salespeople! Guess it's the shift of comms from PBXs to IT - about time

    Wednesday, February 27, 2008 11:19 AM
  • Does interouteone service the US?  If not - anyone know of any competing service?



    Friday, March 7, 2008 1:21 AM
  • From my conversations with them, they do offer service in the US.  However, they cannot port any numbers - only assign new ones.  I hope this changes for them in the future.


    Does anyone know of any other ITSPs for OCS?

    Saturday, March 8, 2008 11:10 AM
  • Hello Nolan,

    the OCS uses the uaCSTA protocol as defined by ECMA TR/87 to communicate with the PSTN as shown below


    where /other-protocol/ is vendor specifc.

    So what you need is a so called uaCSTA gateway.

    I am working as a developer for a company which has developed an uaCSTA gateway for various types of PBXes from different vendors, e.g.
    • ShoreTel
    • Siemens
    • Avaya
    • Nortel
    • Alcatel
    • Cisco
    • and a lot more, e.g. customizable generic PBX types
    even if did not purchase your type of PBX from one of the vendors mentioned above there is a very good chance that it will work with one of the customizable generic PBX types.

    The uaCSTA gateway you need is called Teamcall Server. For more information please look at  http://ww.ilink.de/en/index.html.

    Wednesday, April 23, 2008 4:59 PM