This document discusses lessons learned from Medtronic's SIP trunking implementation with Verizon. Key points include: - Address network readiness and understand pricing models, as savings from SIP trunking vary based on site dynamics. - Map all call flows to understand how calls will route over the SIP trunks and address considerations like codec and number formatting. - Pilot SIP trunking with non-critical applications and test all call variations before porting over all phone numbers. - Define a capacity strategy like overflow protections and limits to manage concurrent calls over the SIP trunks.

1. SIP Trunking Implementation
Jim Allen
Global Unified Communications Architect
James.R.Allen@Medtronic.com

2. Lessons Learned
• Address Network Readiness
• Understand Pricing Models
– Savings Vary Based on Site Dynamics (for us; Favors
Sites Under 100 Users)
• Get Comfortable with Risk (Savings Based on
Elimination of Local PRIs)
• Map ALL Call Flows
2 | MDT Confidential

3. Call Flow Mapping
Medtronic IP & SIP Call Flow
Verizon Voice PSTN Out Verizon Voice PSTN In Verizon Fax PSTN In Verizon Fax PSTN Out Conferencing Out Microsoft Voicemail Out Microsoft Voicemail In
Verizon SBC Verizon SBC Verizon SBC Verizon SBC Intercall Verizon SBC
MS UM
Server
G.711
G.711
G.729
G.729
G.729
G.711
Acme matches strip 003 and
Called DID lookup via local route
adds SDP with G.711 codec only No digits striped No digits prepended from Verizon
table. Match call routes on net. No digit prepend from Verizon No digit prepend from Verizon
No match routes to Vzb (HMR converts to EO Invite)
G.711
ACME SBC
ACME SBC ACME SBC ACME SBC ACME SBC
Cisco CUBE
G.711 Native RFC 2833
Call routed to cluster based on
Route List Prepends 003 to all
Call routed to cluster based on source SIP trunk or LRT lookup. Call covers to UM. New SIP invite
Off cluster calls sent to Acme outbound DIDs for Fax calls No digits prepended
source SIP trunk or LRT lookup. Faxes split off in specific region to created for UM using G.711 based
G.711 Native RFC 2833
Codec based on cluster regions force G.711 on Region relationship
G.729
G.729
G.729
G.729 Native RFC 2833
G.729 Native RFC 2833
G.729 Native RFC 2833
G.729 – Native RFC 2833
G.729 – Native RFC 2833
G.729 – Native RFC 2833
G.711
G.711
MTP
MTP MTP
IOS SW MTP SW
G.711
IOS SW IOS SW
Res Cluster Res
Res Res
G.729
G.711
G.729
G.729
Analog Analog Analog Analog Analog
Analog
GW GW GW GW GW
GW
79X1 7936 79X1 7936 FAX FAX 79X1 7936 79X1 7936 MS UM
Analog Analog Analog Analog Server
Phone Phone Phone Phone
3 | MDT Confidential

4. Lessons Learned (Cont)
• Outbound ANI Considerations (Masking)
• Start With Non-Critical Applications
• Understand Carrier SIP Requirements
4 | MDT Confidential

5. Delayed Vs. Early Offer Challenge
Verizon today only supports
SIP Early Offer
Verizon Session Border
Controllers
ACME Session Border
Controllers
Tot
Problem:
Cisco Early Offer only supports
G.711 on version 6.x and earlier.
Media Termination Point are also
required for every call.
Call Manager
Cluster
MTP routes media
Cisco IP path through Call
Phone Manager Cluster or
Media Gateway
5 | MDT Confidential

6. Delayed Vs. Early Offer Solution
Verizon only supports
SIP Early Offer today.
Other vendors support Verizon Session Border
varies. Controllers
Solution:
Acme SBC modifies SIP Invite from Call Manager
using Header Manipulation Rule. Acme adds SDP
converting it from Delayed to Early Offer.
ACME Session Border
SDP for voice calls includes G.711 & G.729.codecs. Controllers
SDP for fax calls includes only G.711. Tot
Cluster sends all SIP Invites
as Delayed Offer allowing
G.729 or G.711 codec
negotiation.
Call Manager
Cluster
Media path flows directly from IP
phone to Acme SBC once media is
Cisco IP
Phone established.
6 | MDT Confidential

7. Lessons Learned (Cont)
• Pilot and Test Extensively
– Test ALL Variations
• Local, National, International, Small Markets, Faxing
• Voice mail & UM, Auto Attendants etc
• Route Outbound First
• Port DIDs Last – Most Difficult to Back Out
• Define Capacity Strategy
7 | MDT Confidential

8. SIP Capacity Management
180 total
concurrent calls
PSTN Verizon Session Border provisioned
Controllers
Calls over 100 outbound from Twin
Cities overflow to legacy PSTN
Acme set to only allow 100 calls No restrictions set for
PRIs
outbound on Twin Cities trunk
regional sites
ACME Session Border
Tot
Controllers
140 concurrent calls provisioned on
Twin Cities SIP Trunk
Remote sites provisioned with 1
Twin Cities site used as
call only. BEST allows burst of
overflow protection
PSTN 50 over.
IP Gateways
Cisco IP Cisco IP Cisco IP Cisco IP Cisco IP Cisco IP Cisco IP Cisco IP Cisco IP
Phone Phone Phone Phone Phone Phone Phone Phone Phone
Twin Cities Metro Area Remote Site Remote Site
8 | MDT Confidential

9. Questions
9 | MDT Confidential