SIP Issues

Unanswered Question
Mar 18th, 2008

I was wandering if some one can help me out ..... I got few questions , basically I be using SIP and need some general info.....

How many SIP proxy server we need for 60 IP Phones?

If we use SIP proxy server do we still need redirect server?

Do we need a separate server for authentication or SIP proxy server will do authentication...

How we can access voice mail from home or outside office do we need VPN or there is some other way?

If I need to transfer calls from within the office do I need a PBX or it can be done via SIP?

Thanks for your help in advance

I have this problem too.
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Paolo Bevilacqua Tue, 03/18/2008 - 10:39

Hi, are you with cisco? There are internal resoruces for you internal guys to answer questions.

However, which kind of IP phones are you talking about ? If cisco, you can use a 2851 with a feature called cisco callmanager express to control up to 72 phones. In this case, the reccomended protocol is SCCP not SIP, because it gives you more features and it's easier to use.

It does everyt call transfer, and any feature like a PBX does.

If you are evaluating Cisco IP phones nor Cisco callmanager or callmanager express , sorry, that is not the right forum for the question.

oilyas Tue, 03/18/2008 - 10:47

Just started in CISCO so know not sure about things :) Basically we will be using IP phones but we want to use SIP not the SCCP thats the project requirement :( and need help for SIP

Paolo Bevilacqua Tue, 03/18/2008 - 11:07

Obtain a 2851 or equivalent router and you will be able to control all the phones with it. All the documentation is under "cisco unified communications manager express". I recommend you use cme version 4.1 or 4.2 and there's a section dedicated to SIP phones.

The TME for CME is Tony Huynh and I suppose you can consult him freely.

Hope this helps, please rate post if it does!

oilyas Tue, 03/18/2008 - 11:18

Hi mate,

Thanks for your help, My problem is that my client dont want to use cisco unified communications manager express at all the only protocol they want to use is SIP every thing with SIP ? what you recon to use SIP we need cisco unified communications manager express license , as i was been told to use SIP we dont need Call manager or any thing we just need to install SIP server and the server has to communicate with the router and stuff.... Thanks man for your help really appreciated

Paolo Bevilacqua Tue, 03/18/2008 - 12:28

Hi, you can configure CME to work in SIP and load SIP image on the phones. Let the account manager sort out the licensing issue.

If you client doesn't want cisco cm or cme, it can still use the cisco phones with a third-party sip proxy, but there will be many problems, it will not be a good design and will not be supported by the cisco tac, so I suggest you do not take this route.


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