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Sip Provider UCM trunk or IP2IPGW

As I understand one can configure a sip trunk (to sip provider) directly from the UCM6.1 server, or set the SIP trunk to terminate on Voice gateway (running as IP2IP) gateway. In the latter, we'd run h.323 from voice gateway to UCM6.1 and Sip from Gateway up to provider.

What are the pro's and cons of each method? In our's, we will have the PUB in a collocation facility and SUB at main office. Then there will be another branch office.

Without knowing all the details, I would image that it would be better to run sip trunk off ip2ip gateway at each location (HQ and branch) as if the branch lost connectivity to UCM, it could still use sip trunk in SRST mode. Is my thinking on track?

Any and all pro's and cons would be greatly apprecaited. Found one document but didnt' give granualar details.


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Re: Sip Provider UCM trunk or IP2IPGW


Re: Sip Provider UCM trunk or IP2IPGW

I would recommend ISDN ;-) You set it up for 10 mins and then have no problems.

If you go with an ITSP and multisite deployment you'll be setting up the connection at least for a couple of weeks, then you'll realise that everything has gone wrong, 50% of calls have troubles and have another 3 months debugging and troubleshooting with TAC... unless you go with g711 as the only codec, slow start H.323 with no tunneling and no supplementary features :) but still have the question if someone that doesn't support that will be able to call you.

Re: Sip Provider UCM trunk or IP2IPGW

Yes you can configure a SIP Trunk directly from UCM6.1 to a provider. I'm currently doing at one of my customer sites with no issues. One thing for sure is that it is all depended on the provider switch. I've seen some issues with "Early Media Detection", transferring, hold and other supplemental services. Again, it is all depended on the type of switch. Some providers require you to have a gateway with a lot of MTP resources (CUBE) so that they can support the supplemental services.

One thing is to keep in mind is how the trunk is going to send the calls inbound to the publisher if the subscriber goes down and vice versa. You will need to make sure that the provider can direct the calls to two devices with in the SIP Trunk. Send calls primarily to one device, if fail then go to the second device, etc.....

I hope this helps.

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