Connecting 7960 IP phones directly to PC

Hi,

I am trying to find out if the following is actually possible to do.

I have a small experimental network of PCs running Linux with network
configuration controlled dynamically via software running on a Windows
machine which alters the configuration of a 2950 switch to create VLANs etc
which in essence break and make links between nodes. There is also
software running on these nodes which simulate different network effects
such as restricting bandwidth, packet loss, delay etc. What I would like
to do is to connect some 7960 phones to the nodes and then send calls
across the network to see how calls are affected by different network
effects.

Is it actually possible to do this? If so how? Would it need something
like a SIP server running on each node or maybe CCM running on the Windows
machines?

I'm not too familiar with VoIP networks so forgive me if this is trivial.

Many thanks for any help.

Pete

--
Pete Calvert
Scientist
Mobile Secure Information Networks
QinetiQ
(remove NOSPAM to reply)

 

Hi,

You will need a CCM running because the ip phones are totally dumb
without one.

 

That is not true. If you put SIP software on them, you can place calls from
phone to phone just fine.

 

If you go SIP, there is plenty of open-source gatekeeper software for
Linux.

 

So if I use SIP how would the network be setup. Would it be a case of
connecting the phone to a PC (via a hub/switch) then setting up the phone
to talk to the SIP server. Would the SIP server take care of routing to
other phones? How would the phone know what numbers could be called?

I've been reading a bit about SIP and it seems to be able to do what I
want, but I don't have practical experience in actually setting up VoIP
networks so I don't know how this will work.

Thanks for the help so far.

Pete

 

If you only have two phones, connect both to the same hub/switch and then set
one as the SIP server for the other and vice versa. This should work for calling
from one phone to the other. With the Cisco ATA 186, you can dial a number like
"123**192*168*0*1" to call IP address 192.168.0.1, not sure if this is possible
with the 7960. Otherwise, for a simple test, you can install Asterisk on Linux
(http://www.asterisk.org). Asterisk is a softswitch which supports H.323, SIP,
MGCP and I believe even the Cisco proprietary Skinny protocol.

 

What I actually want to do is connect the IP phones to PCs so the VoIP
traffic is sent through the PC so that our bespoke piece of software can
apply different network effects. Having thought about the problem a bit
more I see there are some other issues:

1) If the CCM is placed on the control machine in the network then all the
call setup traffic would have to go by a seperate LAN to the VoIP traffic,
which I don't think is possible with the 7960 phones.
2) I'm don't think it will be possible to use SIP on the phones as the same
phones will be used in a different network controlled with a CCM, which
would mean loading and reloading of firmware which I think would be too big
a task for the customer.
3) The nodes within the network are running Linux so AFAIK there is no way
of running CCM on them.

There are however DTEs which connect to the Linux nodes, so I think a
possible solution would be to connect the phones to the DTEs and then run
CCM on each of the DTEs.

A few questions about this solution:

a) How does the licensing for CCM work? Would I be able to buy one 100
user licence and be able to run CCM on all the DTEs, or would it require a
licence for each DTE?
b) In this solution would it be simple to get the CCMs on the DTEs to talk
to each other.
c) Does anyone have a feel for the amount of overhead traffic there would
be between the CCMs

Thanks

Pete

 

So if I use SIP how would the network be setup. Would it be a case of

Is the Skinny protocol derived from SIP?

 

No idea. You might want to ask on the Asterisk mailing lists (see
www.asterisk.org), they should know as they implemented a Skinny channel driver
for Asterisk

 

How do the Linux boxes do this? Are they routers or are they bridges?
They could be both, it merely depends on what your traffic manipulation
solution can deal with.

Why not just establish a routed network with a CCM somewhere? As long
as you can reach any IP in this network, the phones will work and find
their CCM (just configure them manually).