some calls from remote sites can now cross your WAN to use a centralized unified communications SIP trunk at a campus site. Ensure that SIP trunk codecs and bandwidth needs are understood. Schedule upgrades or reconfigurations of your network prior to Step 3 of the SIP trunk implementation plan. Determine how traffic from traditional Time Division Multiplexing (TDM) applications, such as fax, modem, point-of-sale credit card authorization, alarm monitoring, and telemetry will be handled while more common voice calls use a SIP trunk. These applica- tions might continue to use your existing PSTN gateways until SIP interconnection offer- ings reach greater maturity. Chapter 6 and Chapter 7 provide extensive coverage of network design implications to assess. Emergency Call Policy Determine call routing for emergency calls from all sites that will start to use SIP trunk access to ensure that the number and location information is correctly delivered to emer- gency authorities within the local laws of each site. Discuss the routing of these calls with your SIP trunk provider and, if appropriate measures are not in place, continue to use your traditional PSTN gateways to provide emergency call access. When the SIP trunk is down, mobile phone access for emergency calls to the PSTN might be acceptable in certain geographies. If not, your traditional PSTN gateways might con- tinue to provide service to these call types. The outcome of this assessment might deter- mine the user communities chosen to participate in the pilot and the initial phase of pro- duction service. Define Production User Community Phases There are different ways to approach production roll out of SIP trunk service to your net- work, and there are different reasons for starting with a particular call pattern or user community. This is probably the hardest step to provide a single direction of guidance to because there simply is not a single best way of doing it. Some enterprises start with their contact center operations; others leave those for the last