VoIP Infrastructure

Omoseten used Ask the Experts™
Can someone please confirm for me that the under-listed are all that are required to implement VoIP amongst Six offices (A headquarters and 5 branch offices located at different locations of minimum of 120 miles and maximum of 980 miles apart
Existing facilities: LAN at the HQ; Cisco Switch 3750G (one core switch); four Cisco Switches 2960 – 48 port with PoE capability; VSAT for Internet Access (there are Eighty users at the Hq)
Branch offices have identical facilities: One Cisco Switch 2960 24 ports with PoE capability; VSAT for Internet Access (Twenty users in each of the branch offices)
I am completely new to VoIP; I have red many literatures on it though. But I need confirmation to know if what I am about proposing is all that are required for the project.
At the Headquarters
1.      Cisco Router 2821 Voice Bundle w/ PVDM2-32,FL-CCME-48,SP Serv,64F/256D (Cisco part #: CISCO2821-CCME/K9) for IP Phones
2.      Cisco 112-FXS Bundle, VG 224, Analog Phone Gateways for the existing analog phone set
3.      Check Point UTM Firewall
Branch Offices
1.      Cisco 2811-V/K9 Voice Bundle, PVDM2-16, SP Serv, 128F/512D
2.      Check Point UTM Firewall
Please I am open to more useful ideas
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Sr. Systems Engineer
Top Expert 2008
Make sure you check the PoE budget on each switch, and the amount of power you need for each phone. Which IP phones are you proposing? For example, you cannot put more than about 24 PoE phones on a 48-port switch unless you get something like the 3560-E series. The 2960's should be fine if you have enough of them.

You don't have anything for voice mail. There is a CME/CUE bundle that has Unity Express voice mail module.

I'm assuming that you are planning to use the Checkpoint and VSAT to create site-site VPN's and forward calls between offices? Beware of the latency on the vsat links. You  might not be happy with voice quality.

You might also want to add extra DSP's with adding another PVDM2-16 or more. To support 80 users, 32 probably just isn't enough. You would have to have call metrics for how many total calls on  normal busy hours, and conferencing to use Cisco's DSP calculator.

The 2800 series routers are being phased out. The "next generation" routers are the 2900 series and you should be able to get the same basic CME bundles. The nice thing about them is they have DSP-3 that supports both voice and video. This is a project that will probably be in place for the next 4-5 years at least, so why not start out with the very latest?

I would also highly recommend consulting with your local Cisco office and bounce it off their Sales Engineer. Also ask for a recommendation for a local certified Cisco partner to help you with the implementation.


Thanks very much for all the useful tips.
I am actually proposing Cisco IP Phone 7911G VoIP phone or Cisco Small Business Pro SPA922 1-line IP Phone with 2-port Switch VoIP phone depending on which is acceptable.

"I'm assuming that you are planning to use the Checkpoint and VSAT to create site-site VPN's and forward calls between offices? Beware of the latency on the vsat links. You  might not be happy with voice quality"' ....Yes we are using checkpoint and VSAT for site-site VPN and call forwarding between offices. As regards latency, we intend to use same ISP for all the offices and also enlsit the cooperation of the ISP in the implementation of QoS for the VoIP, with the hope that we won't run to a brick wall.
Please let me know why I still need additional PVDM2-16 at the Hq. My understanding is that Cisco Router 2851 or its 2900 series equivalent fully licensed will be able to deliver maximum of 96 IP phones and adding cisco VG224 Analog Gateway (this will be additional 24 VoIP capable analog phones)  for the existing analog handset will give more than sufficient number of VoIP phones for eighty users at the Hq. Is there any implication you are suggesting that is not clear to me yet?

On a different note is there any need for FXS card since we are installing only IP telephones at the branch offices?
Thanks for your advice on usig cisco certified engineer. I will surely get one at the stage of implementation.
Again thanks for your tips.
Les MooreSr. Systems Engineer
Top Expert 2008
You only need FXS at branches if you need fax machines there. You  might consider  FXO modules with a POTS line or two at a branch just in case VSAT is down they can still make calls and at the very least call 911.

Whether or not you need the additional PVDM DSP at the main office depends on the total call volume, peak number of calls, fax pass-through, etc. You did not say in your initial post what you are planning to use for PST connections. Are you planning a SIP trunk, PRI, POTS, or what? With years of experience, adding additional DSP cards up front saves money later. It's not a lot extra. It's not a license issue. Cisco packs bundles with minimum capabilities. Just like Microsoft said Windows NT could run on 16Mb RAM. Sure, it ran, but you couldn't do much with it. The 2821 bundle is outfitted to support an initial 48 users, no the maximum 96. This also means that you need licenses for all IP phones between 48-80.

The SPA phones are not supported on the UMCE bundle. Only the 7900 series phones are.
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Thanks very much. The plan is to implement SIP trunk. I am begining to have a rethink over the choice of 2821 for the HQ. It may be necessary to change it to 2851 or 3825 at best to allow enough capacity for expansion. Again, the essense of VG224 is to allow additional 24 ports for the existing Analog phones.
Thanks for drawing my attention to the compatibility issue as regards the SPA phones. I will try and look for the cheapest of the 4900 series.
Again, I never thought of separateDSP cards before now because my impression was it will be bundle with the routers? How many of these will be ideal for a network of this capacity? Will it be required in all the locations? What value will it add to the project?


I still need lrmoore to respond to my last comment.
Les MooreSr. Systems Engineer
Top Expert 2008

The voice bundles have a PVDM-16 and that will be plenty for the branch offices. Their primary use is analog to IP. Analog POTS lines to IP phones require DSP's.
With the DSP's at the HQ, you can setup more conference calling capability, more fax capability, or modem pass-through capability to what sounds like quite a few analog devices.

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