[cisco-voip] Design question--- More phones, do I need more Call Managers or not?

[Tim Reimers]

Hi everyone-

 

I have a general design question for you all - looking for input on what
you think-

 

System stats:

School district phone system-

7 schools, one Central Office

 

 

Currently, we run 460 phones at 8 sites- all over Gigabit fiber with a
6509 at the core at the Central Office.

 

Mostly 7905 phones, with about 150 7960 phones

Two 4.0 Call Managers- publisher, subscriber

Unity 4.0

Cisco Emergency Responder

Two ISDN PRIs, running 30 channels out of the available 47, handled by a
2651XM with the PRI NM module.

8 sites at this time.

Each site has a 1760 (one 2651 at the middle school) router that runs
SRST and handles emergency calls.

Each router has 2 POTS lines attached, for two calls outside the system
when the link to the CO is down or a 911 call needs to go out from the
address of the school.

Voice switches are 3560-24/48-PS switches - they also terminate the data
traffic going back onto the fiber to the Central Office.

Most schools have only one voice switch per wiring closet, up to 4
switches per school

 

 

We're getting ready to add on the high school now- it is 90 or so
classroom phones, and probably about 50 or so 'office' 7960 phones.

 

I anticipate needing to turn on the other channels in the PRI..

 

So--- having laid out what we have, let me ask a few questions-

 

the major question is this-

 

The vendor who put in the system and is a bidder on the highschool
addition wants to put in a third call manager 

I recall that the CCM is capable of up to 2500 phones--- so I doubt that
with about 700 phones we're anywhere near stressing the system.

I don't know how many phones SRST supports nowadays--- I think I recall
25 phones.

That's about all I can think of that would justify a whole third CCM
installation for only 150 or so phones...if you wanted more than 25
phones up and running in SRST mode.

 

Anyone got any ideas on design for the highschool?

There's going to be a 4006 at the core, but not running voice - that'll
be separate switches in that building, and all other buildings...3560
switches I'd imagine...

 

Thanks for any input you guys can offer!

 

Tim

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