CM over the Internet

[adignan]

Horrid question I agree but I have a customer who wants to place phones at a remote site and here is the catch. They have been doing VOIP over the internet between two sites for quite a while now. They recently put in CallManager at one of the sites. They would now like to place phones at the other site, but the phones would register to CM through the internet (not too mention ICD agents as well). They refuse to purchase a point-to-point or even create a VPN tunnel. They have a T3 at each site. There argument is that they have been conducting VOIP (4 phones hangin off fxs ports on a router) for years now and see no reason why it won't work now. Just for fun I would like to hear some feedback on how terrible this is and some of the reasons this should not be attempted. Security, bandwidth, reliability, etc.

Thanks

[travis-dennis_2]

Well partner, I think you picked the wrong place to get this shot down. Too many people here (myself included) are doing this and doing it with better than PSTN MOS scores. The official Cisco line is that this is not supported since you cannot get QoS over the Internet. True, but if you can get an SLA that keeps your delay, jitter and packet loss to an acceptable minimum, know what you are doing on your routers, don't over-subscribe the pipe and (my personal opinion but I know others who do not abide by this and are fine) stay on the same provider from point A to point B it works very well. I also take it a step further and do VoIP over VPN for those of you out there that are security minded. I love it. It works great if you know what you are doing.

[jvanick]

We're doing this too, however... I'd say that you at least want to put in some kind of minimal VPN, at least a GRE tunnel or Cisco VPN3000 (altiga) solution...

The possibilites for toll fraud are ridiculous if your callmanager and rest of the h323 network are wide open to the internet.

All that being said tho... I'm running with a 3des VPN connection between my office and my house (office has a T1, my house is connected via a cable modem) with a PIX at home, Absolutely NO quality of service ANYWHERE, and things work awesome...

I use both a hard phone (7960 on my desk at home) and softphone for when I'm travelling and the quality is fine. If I fire up a large outlook synchronization or web download I might get a little choppieness on the call, but nothing worse than a good cellphone call.

-J

[adignan]

That is fine for a few phones. There will be at least 50 phones and ICD Agents.

[travis-dennis_2]

Runing g.729 over the link with a T3 you need to do a study to find out on average how many concurrent calls are up and plan your bandwidth accordingly and what is your fall back plan if the calls cross that threshold. It really doess't matter if you have 5 or 500 if you don't over-subscribe and have the configs in place to handle the volume. Okay...maybe 500 is a bit as I can't really speak on that amount but with the right bandwidth 50 should not be a problem. If you do decide to go the VoIP over VPN router don't forget that you can't use cRTP for encryptred packets as they leave the router so do your bandwidth calculations based on that and the additional header indformation that encapsulation produces.