Alan Percy : The SIP Invite
Alan Percy
| Observations by Alan D. Percy on VoIP enabling technology, industry and our personal reach for success.

December 2008

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IP Communications and Opportunities - Question and Answers

December 18, 2008

Some great questions were raised during the most recent webinar titled "IP Communications - an opportunity in a down economy" and I thought sharing the entire list would be valuable.  So here it goes:

Q: What needs to be done to the typical PBX to use SIP Trunking?
A: Most PBXs, Key Systems and other TDM equipment connect to the public network using either analog or T1 trunks here in North America.  In EMEA and other areas, you'll also see E1 and ISDN BRI trunking.  For SIP trunks to connect these legacy systems, a SIP media gateway with matching TDM interfaces is required.

Q: What kind of interoperability issues are there between SIP trunks and IP-PBXs?
A: Right now there are plenty of interoperability issues and while there is some progress on standardization, is seems that it will be a while before you can just "plug and play".  The issue is the looseness of the SIP standard and investment many vendors have already made in their networks.  The end result is that today some either software or hardware device must do the IP-to-IP mediation between the two different formats, converting both signaling and media as required.  I put together a paper on the topic last year that you may find helpful.

Q: Do you see more opportunities in the residential or in the business segment during this recession?
A: It seems that today business are the most eager to cut operating costs.  Residential customers seem to be frozen in their tracks or just cutting the cord to their land-lines.

Q: What new products does AudioCodes have for hosted PBX providers today?
A: We have CPE gateways for the customer premise, large media gateways that connect the hosted application to the PSTN, session border controllers that secure the connection between the service provider and CPE, and media servers required for conferencing, announcements and other applications.  Check out our new web site at and use the application navigation page for more ideas.

Q: Does SIP Trunking replace the existing T1 completely?
A: In many application - Yes.  The legacy TDM Voice T1 is completely removed.

Q: What changes are needed in the TDM PBX to use SIP Trunking?
A: In many cases - none.  The media gateway would be configured to emulate the legacy TDM T1/E1/BRI/Analog trunk allowing the PBX to continue to operate as-is.  In a rare few cases, a few parameter settings within the PBX would need to be changed.  However, there is no need to add any cards or spend any more money on the PBX.

Q: I keep hearing that SIP carrier trunks are not available in all markets? Can you please comment on that .?
A: Some of the SIP Trunking service providers do have a regional focus.  This allows them to better address and service their selected regions.  Others are more global.  When you call a SIP Trunking service provider, make sure you have your service locations in hand and they can tell you if they can service those sites.

Q: On slide 16, what is "OSN"?
A: Open Solutions Network - this is the embedded application server that is part of our partner network program, allowing them to run their applications within the gateway.  You can think of this as an Intel server sand-box within the gateway.  This eliminates a separate server and allows for one-box appliances.

Q: How is VoIP security such as Session Border Controller functions addressed by AudioCodes?
A: How a Session Border Controller (SBC) works is a very complex topic and a paper on our web site explains it in detail, but in a nut-shell it uses a Back-to-Back User Agent to terminate the SIP sessions, allowing the examination of the request and comparing it against a number of security rules.  Once validated, the request is re-issued on the other side and sent along the way.  A similar process may also occur with the media streams.

Q: Can the Mediant 2000 support your SBC module?
A: The Mediant 1000 has an SBC module, but today the Mediant 2000 does not have an SBC module.  An external SBC like our nCite 1000 may fit the application/

Feel free to use the Comment feature to post more questions and keep the dialog going!

IP Communications - An Opportunity in a Down Economy?

December 16, 2008

Thanks everyone that participated in yesterday's webinar.  It was interesting to see the diverse range of participants and responses from the session.

If you missed it, here is some background on the topic:

This most recent economic downturn has far reaching impact on a wide range businesses and industries. In this climate, corporate executives are examining every capital expenditure to ensure there is a quick return on investment and that the expenditures are in line with the strategic goals of the business. This has put many large communications infrastructure capital improvement projects on hold while alternatives are examined more closely. However, even in a down economy there are some very clear opportunities for businesses to reduce current operating costs without large capital expenditures.

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