7960 IP Phone behind a VPN through DSL connecting to CCM on our Network.

[vlaxamana]

Excuse me for my ignorance but has anybody been able to make a 7960 IP phone connect to your Call Manager in your internal network with the 7960 being used from home behind a VPN through a DSL broadband connection.

If there is anybody who had success in this I would greatly appreciate it if you can tell me how you did it.

Thanks.

vladi

vladi.laxamana@therasense.com

[jpstott]

Yes, and there are several ways to do this. PIX-PIX tunnel, PIX to VPN Concentrator, Hardware Client to VPN concentrator/PIX, IOS router to VPN concentrator/PIX. If you successfully get a tunnel working, your 7960 will be just another node on the LAN that should be able to communicate with the CallManager.

You will want to run your DHCP at the remote location or statically address your phone. Also, you will have better call quality with a decent link speed. Most residential DSL/cable is fast download (384K or better) and slower upload (128K). Try for a 6MB/1MB DSL link if possible. I don't know what is available on the cable modem systems. I have set users up with DES encryption and 3DES encryption and it doesn't seem to have much affect on the call quality either way; at least not as much as the link speed.

I personally have a 384/128K DSL link and I'm ready for a better connection. I'm using a PIX 501 to a VPN concentrator. On some calls, there is a delay which seems to grow as the conversation goes on. Sometimes it is 5-7 seconds, which makes a business call almost impossible. It is interesting to note that the sound quality is excellent always. (I'm using G.711 - I tried G.729 for a while and it didn't help; if anything the voice quality degraded.) I have an average 29ms ping to my CallManager.

Hope this helps; you may want to search this forum further as there are quite a few threads on this topic. Good luck!

[darrick]

The 384/128 connection John is using is sufficient from a bandwidth perspective, but it would appear that his connection suffers from a large amount of jitter. I myself use a 7960 over VPN and get excellent audio quality with less than a second of latency. That's not bad considering my voice travels from Dallas to San Jose over the internet and back to Dallas again over an intranet during most calls.

Darrick

[jpstott]

Darrick,

Thanks for the clarification. I should have noted that I usually get the 'jitters' when my PC is on and I'm in Outlook. (I may be pushing the limit on my 128K. ) I'm sure that the relative location of the remote site (in terms of internet hops) makes a difference as well.

What type of link are you running? Just curious...

[darrick]

To improve simultaneous use of a 7960/7940 and a PC you should plug the Phone into your access device (vpn gateway) and plug the PC into the phones PC port. This should improve the audio during simultaneous use. Make the phones QoS enabled switch work for a living. :)

I was doing this with DirecTv DSL with a solid 1.5Mbps down and 128K up. However I have since gone to a full T1. I know that doesn't match most home network links, but a Cisco partner that is a CLEC was kind enough to extend their employee discount to Cisco employees and I couldn't pass up the incredible deal.

With the DSL line I ended up putting the phone into a G.729 region. It was working great with G.711, but you do pay a price. Usually I am on the phone with someone working on an issue and needing to send files or check source code in. It took longer due to less bandwidth available. We don't use silence suppression so it also helps to hit mute when sending files.

I now use G.711 and will switch to Wideband when we get VPN access about 1000 miles closer than the current concentrator.

Darrick

[vlaxamana]

I finally got me a Pix 501. My IP phone somewhat works, however, I only have one way voice. Can you advise as to what I possibly am missing.

Thanks.

[vlaxamana]

Thanks for the input John. I think I can figure out assigning a static ip address to the IP phone. However, where I am confused at is how DHCP will work through VPN. Excuse me for my ignorance again but how will IP phone be a vpn client? I think my question is if I am in the office the switch port on the back of the IP phone of course connects to a drop that connects to a patch panel that connects to a 6500 series SW and the PC port connects to the PC. How would I do this from the standpoint of having a DSL router?

Thanks in advance for any input.

[jpstott]

To run DHCP over your VPN to a DHCP server at your office, you would need a way of forwarding DHCP requests from your LAN at the remote site to the office LAN. I don't know if my PIX 501 can do that, but it does provide DHCP services for my home LAN, so I just set it up to hand out addresses and the appropriate phone settings (66 and 150).