Voice Calls over Internet

[peternnaji]

Hi All,

I have a design for Voice Over internet for three separate locations (Lagos, London and Kenya) as shown in the attached diagram.

The scenario is this:

** There is no private WAN line king all three locations

** The HQ is Lagos

** All three locations have traditional PBX and Analogue Phones (old design)

** All three locations communicate through the PSTN or ISPs

Now, with the introduction of the Callmanager and IP Phones (NO WAN YET), and with the attached design, all IP Phones at the London and Kenya offices are meant to be registerred in the CallManager at the HQ (Lagos).

My questions:

1) How is this possible over the public internet;

2) What IOS features/Capabilities should the Routers at all locations have?

3) What is the required minimum bandwith for each location?

I will be glad for your responses!!

[Adrian Saavedra · Accepted solution]

Hi,

1) How is this possible over the public internet;

Using VPN. I will not recommend you use public Internet for your UC deployment. You'll experience higher delay, jitter, packet loss, no QoS and all of this will trigger a poor end user experience.

2) What IOS features/Capabilities should the Routers at all locations have?

Since this is a multisite centralized deployment, you should deploy SRST/CME-as-SRST for your branch offices. Use latest UC enabled IOS.

3) What is the required minimum bandwith for each location?

Depending on the number of calls to traverse WAN, you can calculate BW with the Cisco BW calculator tool:

http://tools.cisco.com/Support/VBC/do/CodecCalc1.do

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml

Hope to help, please remember to rate if it does.

Regards,

- Adrian.

[Brandon Svec]

I would just like to clarify that VPN only offers security (and is still recommended conection method) however, it will do nothing to help guard against potential delay, jitter, packet loss or QOS over the public internet.  If anything it will make things slightly worse by adding some additional bandwidth and processing requirements.

Brandon

[ronpatel]

Hi

If you want good design, you can have phone proxy feature.

Cisco ASA supports phone proxy feature which allows phones from internet to regeester to In side network CUCM.

http://www.cisco.com/en/US/docs/security/asa/asa82/configuration/guide/unified_comm_phoneproxy.html

Regards

Ronak Patel

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