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this section covers call routing in an H.323 video network using the cisco gatekeeper and IP/VC equipment
chapter 7 call routing this section covers call routing in an H.323 video network using the cisco gatekeeper and IP/VC equipment. calls are router to and from, many different devices in a number of different ways. this section cobers the different type of calls routed and methods used. this chapter contains the following sesions: • call routing scenarios. • incoming PSTN to H.323 call routing • inbound PSTN call routing in a single zone • inbound PSTN call routing in multi zone environment • enter zone call routing using hopoff statements • enter zone call routing using directory gatekeeper Call routing scenarios: there are four types of calls that win be routed in an H.323 network(1)H.323 endpoint to H.323 endpoint using E.164 address, (2)H.323 endpoint to H.323v endpoint using H323-ID, (3)H.323 endpoint to an H.323 service (gateway or MCU),(4) incoming PSTN to H.323 endpoint or service. each of the four routing scenarios is discussed below. • routing calls between H.323 endpoint is the simplest type of call routing in an H.323 network. Dialing in a single zone require the endpoint initiating the call to enter the E.164 address of the endpoint being called (with in most cases will be a 10 –digit fully qualified E.164 address, including the zone prefix and 7-digit number of the endpoint ). if the call is an inter zone call thoinitiator must enter the zone prefix (if the dial plan is using 10 digit E.164 addresses the zone prefix is part of the E.164 address) and the E.164 address or the endpoint being called. using this dial string is similar to dialing outside ones’ area code in the telephony world (in multi zone networks service prefixes for MCUs and E.164 addresses should contian the zone prefix). • routing calls between H.323 endpoints using H.323-ID requires that the calling station dial the H.323-id of the video terminal being called. H323-IDs are only supported for alls from video terminel to video terminal, or video terminal to video terminal adapter(VTA). when using a VTA care must be take in addressing as some H.320 units cannot send alphanumeric strings. in these cases, E.164 address are the only route table mecchanism. between zones, DNS (domain name service) may be used to reach the H.323 –ID of an endpoint registered to a remote gatekeeper. this is done by dialing “H323- ID@domain” this allows the gatekeepers to resolve the remote zone destination via DNS. • routing calls from an H.323 endpoint to a service is also fairly simple. in a single zone an H.323 endpoint will dial the service prefix, followed by either the conference ID(for an MCU call), or ISDN telephone number of the H.320 endpoint. routing inter zone calls to service is also done using the service prefix, but the service prefix will now contain the zone prefix for MCUs, and use hopoffs for gateways. • routing calls from the PSTN to H.323 endpoints or services can use of four methods: MSN/DID, IVR, TCS4 or by using a default extension. below each of the four PSTN to H.323 routing methods will be defined, and then applied to a single zone and multi zone enviroment. figure 7-1 illustrates a multi zone network with video terminals and services in each zone. table 7-1 shows the dial strings for the four intra and inter zone call typer. Below dial strings for the scenarios in figure 7-1 are listed. 1. H.323 endpoint to H.323 endpoint : intra zone call tsmith to jbank: tsmith dials 4085248071 inter zone call tsmith to jcox: tsmith dials 7207125543 2. H.323 endpoint to H.323 endpoint using H.323-ID: intra zone call tsmith to jbank: tsmith dials jbank@cisco.com inter zone call tsmith to jcox: tsmith dials jox@cisco.com 3. H.323 endpoint to service: intra zone call tsmith to H.320 system: tsmith dials 91212555212 . chapter 7 call routing this section covers call routing in an H.323 video network using the cisco gatekeeper and IP/VC equipment. calls are. PSTN call routing in a single zone • inbound PSTN call routing in multi zone environment • enter zone call routing using hopoff statements • enter zone call