I’ve always been a little confused by H.323 vs MGCP and as it relates to the overall configuration within Call Manager and the Gateway. It’s was probably due in part to the fact that I never had the opportunity to actually configure H.323 or support it until recently. The Telecommunication Standardization or ITU is actually responsible for governing or maintaining the standards around H.323 and the protocols to which provide audio and video communication sessions over the network.
The ITU-T H.323 Protocols Suite
- H.225: Used for narrow band RAS Signaling
- H.225: Used for Call Control setup and Signaling
- H.245: Used for Media Control and Transport
Define the card type for the Serial Controller.
Router#configure terminal Router(config)#card type t1 0 0 Router(config)#
Configure the clocking for the ISDN controller channelization.
Router(config)#network-clock-select 1 T1 0/0/0
Configure the ISDN related controller time slots.
Router(config)#controller T1 0/0/0 Router(config-controller)#cablelength long 0db Router(config-controller)#pri-group timeslots 1-24 Router(config-controller)#description H.323 Gateway Router(config-controller)#exit Router(config)#
Configure the voice services and related H.323 protocols
Router(config)#voice service voip Router(config-voi-serv)#allow-connections h323 to h323 Router(config-voi-serv)#fax protocol pass-through g711ulaw Router(config-voi-serv)#modem passthrough nse codec g711ulaw redundancy Router(config-voi-serv)#exit Router(config)#
Unlike MGCP there is no need to back haul the D channel over Layer 3
Router(config)#interface Serial0/0/0:23 Router(config-if)#description H.323 Router(config-if)#no ip address Router(config-if)#encapsulation hdlc Router(config-if)#isdn switch-type primary-ni Router(config-if)#isdn incoming-voice voice Router(config-if)#no cdp enable Router(config-if)#exit Router(config)#
Configure a loopback interface and bind H.323 gateway voip source address
Router(config)#interface Loopback0 Router(config-if)#ip address 10.254.254.1 255.255.255.252 Router(config-if)#h323-gateway voip bind srcaddr 10.254.254.1 Router(config-if)#exit Router(config)#
From within Call Manager create the H.323 Gateway and Route Patterns
Create a dial peer that can be used for 10 digit dialing outbound
Router#configure terminal Router(config)#dial-peer voice 1 pots Router(config-dial-peer)#description 10 Digit Dialing Router(config-dial-peer)#destination-pattern 1[2-9]..[2-9]...... Router(config-dial-peer)#port 0/0/0:23 Router(config-dial-peer)#exit Router(config)#
Create a another dial peer that can be used for 11 digit dialing outbound
Router(config)#dial-peer voice 2 pots Router(config-dial-peer)#description 11 Digit Dialing Router(config-dial-peer)#destination-pattern 91[2-9]..[2-9]...... Router(config-dial-peer)#port 0/0/0:23 Router(config-dial-peer)#exit Router(config)#
Create a dial peer used for the second leg of the call destined for the Publisher
Router(config)#dial-peer voice 3 voip Router(config-dial-peer)#description Publisher Router(config-dial-peer)#destination-pattern .T Router(config-dial-peer)#session target ipv4:172.16.20.10 Router(config-dial-peer)#exit Router(config)#
Create a dial peer used for the second leg of the call destined for the Subscriber
Router(config)#dial-peer voice 4 voip Router(config-dial-peer)#description Subscriber Router(config-dial-peer)#preference 1 Router(config-dial-peer)#destination-pattern .T Router(config-dial-peer)#session target ipv4:172.16.21.10 Router(config-dial-peer)#exit Router(config)#
The final dial peer is used for first leg of the call inbound
Router(config)#dial-peer voice 5 pots Router(config-dial-peer)#description Incoming Calls Router(config-dial-peer)#incoming called-number . Router(config-dial-peer)#direct-inward-dial Router(config-dial-peer)#forward-digits all Router(config-dial-peer)#exit Router(config)#end Router#
