Suggesion required for external sip trunk to VG or CUCM

[Zahir Raihan]

We have  CUCM  version 8.0 and a cisco 2811 voice router in our contact center lab .for internal IP Telephone on Contact center we have a local lan configured which includes both the gateway and cucm .Now we want to connect to the external sip server for both inbound and outbound call routing.The Scenirio is that We have to use a real IP address  for forwarding and recieving calls from external sip server. Now I'm looking for experts suggessions whether its best practice to terminate the real ip on voice router and then forward the calls to the CUCM or its better to terminate the real ip  at CUCM secondary NIC.It would be helpful for me if anyone can provide with some configuration and Design example.
Thanks In Advanced.
Zahir.

[Tim Smith]

Hi Zahir,

Definitely use your router.

You want to look at using the CUBE feature set.

Without hacking, it's not even possible a unique ip address on secondary nic of CUCM.

Remember CUCM is supposed to be a locked appliance OS.

CUBE will let you do address hiding with media flow through and also allow you to do a SIP REGISTER to your provider for authentication.

Probably the 2 most important things you will need to get this going.

These are just the tech bits to get it up and running, also lots of good design reasons you want this little CUBE fellow in between.

Do some research into CUBE, search cisco.com - you will find good docco and config examples.

There's also now a good Cisco Press book - think it's called "SIP Trunking"

Cheers,

Tim

[Zahir Raihan]

Hi Tim,

Thansk for you valuable suggessions. I need some configuration examples for the same. Let me describe our scenerio first

external sip server --->  (2800 voice router)-->CUCM...

the 2800 router have two Fasthethernet interface of which one is used for contact center local LAN(fa0/0) and the other interface is connected to the public network . we are to use  an external sip server (service provider) address which forward incoming call to outer routers Public IP address. now we need to redirect the incoming call to CUCM and both make outbound call from ip phones registered with cucm. Note that cucm is connected in the private network which resides in the network of fa(0/0) of the  2800 router. I've tried with simple dial peer configurations on the router with session protocol sipv2.

//// for outbound calls        

dial-peer voice 200 voip

 destination-pattern .

 session protocol sipv2

 session target ipv4:

 dtmf-relay sip-notify
 codec g711alaw

On CUCM the router is registered as a h.323 gateway. now when i make calls from IP phones registered with CUCM

the debug ccsip calls on router

shows sip disconnect cause (503). and the IP phones play fast busy tone.

could you please help me with some configuration examples...

Regards

zahir

[Tim Smith]

Hi,

You really need to check out the CUBE config guide. It has examples, and all the detail you need to get started.

One basic thing that may be forgotten is to allow the voip to voip based on your required protocols.

For example...

voice service voip

     allow-connections h323 to sip

     allow-connections sip to h323

I'd also consider just to keep it simple use SIP to your CUCM. This keeps it SIP all the way through and makes it a bit simpler. There are also limitations when interworking between H323 and SIP. CUBE guide covers them.

Cheers,

Tim.