2. Choosing the right protocol in a Cisco Unified CallManager environment
Basics of Protocols
Choosing the right protocol in a Cisco Unified CallManager environment

3. Introduction
Who am I?
Louis R. Marascio, former CTO of Metreos Corporation
Metreos was acquired by Cisco Systems in June 2006
For the past 6 years I have been building a development platform, tools, and applications for large Cisco IP Communications customers
In this session I hope to share with you knowledge learned through painful trial and error in the real world

4. Who Cares About the Protocol?
Pragmatism wins in the dynamic world of IP communications
End-users DO NOT care if the call was handled with SIP, H.323, JTAPI, or SCCP
End-users DO care if the protocol chosen to handle the call does not provide the feature set they want
Choosing a protocol is like choosing a programming language: determine which protocols can solve the problem and then pick the one you are most comfortable with

5. Line Side vs. Trunk Side vs. CTI
Legacy terminology carried over to the IP communications world
Capabilities differ depending on how you present your application to the telephony system
Traditionally only CTI was available, but IP communications enables us to leverage the line and trunk side as well

6. Line vs. Trunk vs. CTI (cont)
PROS
Dialed number modification
Very easy to setup
Straightforward routing
CONS
Limited access to features
PROS
Call routing
Built in failover & redundancy
CONS
Complexity
PROS
Access to features
Scalability
CONS
Increased administration
Line side device limits
Licensing

7. Example: Outbound Dialing & Bridging
A very useful call flow when building many types of applications
Involves bridging two independent calls while retaining call control ownership
Often used in application initiated calling scenarios
IPC Application
HTTP
“Other” App
Signaling
Media
Application maintains control over the call and mixes/bridges the bearer path

8. Example: Outbound Dialing (cont)
Trunk interfaces are typically best suited for this type of application
Modification of calling number is an important aspect, make the call look like it is coming from another entity
H.323 or SIP trunk side is the best choice
If you need supplementary services and don’t have CCM 5.0 then use JTAPI, but you won’t be able to do calling number modification

9. Example: Inbound Call Routing
A very common, basic, but useful call flow
Used by legions sales guys when describing the “benefits” of VoIP (“You see, you take the inbound call, perform a database ‘dip’, and send it to the last agent they spoke with”)
DN:
Redirected DN: 27532
IPC Application
Application no longer controls the call after redirection
Signaling
Media

10. Example: Inbound Call Routing (cont)
Traditionally the realm of JTAPI route points
In CallManager versions prior to 5.0, JTAPI is the best and preferred way to accomplish this
In CallManager 5.0 you can leverage SIP trunks and a redirect (302) response to achieve a similar result
Depending on the features you need, SIP may not be enough in 5.0 (Calling Search Space modification per call, calling name or number modification, etc)

11. Basic (mostly true) Rules of Thumb
Choose trunk side protocols for easy manipulation of calling party number
In general, avoid CTI if you can
Line side protocols are useful when you need access to phone oriented features, but they tend to be harder to setup and manage
Abstract yourself away from the protocol, it will make your life much easier as the underlying system evolves

12. Contact Information
If you have any questions please feel free to contact me:
Louis R. Marascio
Cisco Systems, Inc.