428 APPENDIX D: CONNE XTIONS H.323 GATEWAY■ By modifying the dial plan.You can configure the speed dial numbers to include an appendedextension if a person in one NBX system needs to make frequent calls tosomeone in another NBX system. Alternatively, you can configure the dialplan to route these calls seamlessly to the caller.NBX system calls to outside numbers must use IP addresses or hostnames. The ConneXtions software automatically converts host names totheir corresponding IP address.Voice PortsMultiple voice ports allow the Auto Attendant to respond to multipleincoming calls at the same time. However, since these ports are also usedby the voice mail system, voice mail inquiries can slow down incomingH.323 calls. You may have to increase the number of voice port licenses.Extension Dial PlansPBX systems can use different dial plans. You must consider dial plandifferences when setting up calls between systems. Dial plans differ intheir use of leading digits, number of digits, and excluded numbers. Formore information, see Chapter 2.Extension DelayCall setup times for digital connections, compared to analog connections,are instantaneous so there is no need to include a delay between theIP address and an appended extension.Incoming H.323 calls to an NBX system usually go directly to theAutomated Attendant. Although the Auto Attendant can respond withvoice instructions, the call does not have to wait until the end of the voiceinstruction to respond. The Auto Attendant accepts extensions whetherthey are entered manually or as part of a speed dial number.Class of Service The use of an H.323 gateway affects the Class of Service assignmentsthat are applied to extensions because:■ H.323 calls use IP addresses instead of the familiar numbers that areused for public switched network calls (different dial plan).■ The cost of an H.323 call is distance-independent, so you do not needto limit long distance calling for cost reasons.
