Intl SIP Design - Best Practice

[Luis Sanchez]

I'm having a little difficulty designing our SIP VoIP network.

I currently have my Cisco Voice Gateway Router with CUBE licensing accepting SIP calls in Florida and my Call Manager and majority of my users are also Florida.

We just opened a 20 man office in Spain. Now the fun begins.  All I have in Spain is and ASA 5505 with a persistent VPN tunnel to my Florida ASA 5510.

Option 1 - Place a Voice Gateway in Spain and call up a local company to deliver a SIP trunk to the gateway. When the call comes to the gateway have it go over my VPN tunnel to my Florida Call Manager only to come right back to Spain to the endpoint.

Option 2 - Have the SIP trunk with the Spain numbers come to my Voice Gateway in Florida which is local to the Call Manager. Then, go over the VPN tunnel to the endpoint.

The majority of calls will orginate from Spain. It would be nice if the call did not have to come back to the Call Manager in Florida at all.

Any thoughts?

[paolo bevilacqua]

That is correct, a give site call show use local service to make and receive calls especialy when the alternative is across the atlantic.

[Luis Sanchez]

Thanks Paolo.  Can you explain a little more. Are you saying that Option 1 is the best? Thanks!

[paolo bevilacqua · Accepted solution]

Option 1. With correct configuration, RTP will stay in remote site and not travel over the WAN.

Then since you have installed a voice gateway, you can configure it with CME for the added benefits of a simple, powerful system not depending from anything else.

[Luis Sanchez]

Paolo, Great answer. The RTP stream is where I was confused. I wasn't sure if the RTP stream had to go across the Atlantic twice. Sounds like, with proper configuration, that a call can orginate from Spain and stay in Spain without having to travel across to Florida at all. Thanks!  Jon what do you think?

[Zekeria Sammantar]

Have you thought of clustering over the wan. If the end-to-end latency is less than 80ms, it will be supported by TAC

Apply Qos for ICCS traffic. I wouldnt know the latency of a your link. Let me know that usual latency between the sites.

[paolo bevilacqua]

Zekeria Sammantar wrote:
Have you thought of clustering over the wan. If the end-to-end latency is less than 80ms, it will be supported by TAC

What a truly poor practice that is. Additional costs, licensing and complications, remote servers, for little if any benefit but always being on the hook for link interruptions, unsynced databases, and the like.

[Zekeria Sammantar]

Thanks

[Erik Peterson]

How about put a router running CUCM Express in to the Spanish office.  You can terminate either TDM or SIP PSTN service local, and keep most signaling and media traffic local.  You can also set up either H.323 or SIP to CUCM in Florida.  The other consideration is voicemail, or any other apps/capabilities like Jabber or video.  You could tie CME in to Unity Connection, or use CUE.

Depends how independent you want the office to be, and if you want to have to administer a separate system.  I have seen phones and gateways in Asia driven by a CUCM cluster in the U.S., but it was on a high speed MPLS link with low latency and QoS.   If the latency on the VPN is acceptable, and the VPN is fairly reliable, you may be able to live with running the site off of the Florida servers.