Precision Time Protocol 
Tutorial description
This tutorial will guide you for advanced voip configuration in Cisco Packet Tracer 7.1.1 network simulation software. Based on the Cisco's Hierarchical Network Design Model, this simulated network has voip call routing features enabled between two campus buildings with network services (DNS, DHCP ...) centralized in the datacenter.
In a real world environment, the CUCME router would also be located in the datacenter. However, Packet Tracer doesn't seems to support this configuration as IP phones don't register and receive a valid phone number.
Network diagram
Download lab (Packet Tracer >= 6.2)
Configuration tasks
CME-3 configuration
IP configuration
hostname CME-3 ! interface FastEthernet0/0 ip address 192.168.69.254 255.255.255.0 duplex auto speed auto ! ip classless ip route 0.0.0.0 0.0.0.0 192.168.69.1 !
Telephony service configuration
telephony-service max-ephones 5 max-dn 5 ip source-address 192.168.69.254 port 2000 auto assign 4 to 6 auto assign 1 to 5
Ephone declaration and number assignment
ephone-dn 1 number 2001 ! ephone-dn 2 number 2002 ! ephone 1 device-security-mode none mac-address 0090.0C57.C85E type 7960 ! ephone 2 device-security-mode none mac-address 0090.0C20.BA20 type 7960 ! ephone 3 device-security-mode none mac-address 0005.5E9E.2AC5 type 7960 button 1:2 ! ephone 4 device-security-mode none mac-address 0060.5C2D.6220 type 7960 button 1:1
CME configuration
IP configuration
hostname CME ! interface FastEthernet0/1 ip address 192.168.65.3 255.255.255.0 duplex auto speed auto ! ip classless ip route 0.0.0.0 0.0.0.0 192.168.69.1 !
Telephony service configuration
telephony-service max-ephones 42 max-dn 144 ip source-address 192.168.65.3 port 2000 auto assign 4 to 6 auto assign 1 to 5
Ephone declaration and number assignment
ephone-dn 1 number 1101 ! ephone-dn 2 number 1102 ! ephone-dn 3 number 1103 ! ephone-dn 4 number 1104 ! ephone-dn 5 number 1105 ! ephone-dn 6 number 1106 ! ephone 1 device-security-mode none mac-address 0090.0C57.C85E type 7960 button 1:1 ! ephone 2 device-security-mode none mac-address 0090.0C20.BA20 type 7960 button 1:2 ! ephone 3 device-security-mode none mac-address 00E0.A340.E430 type 7960 button 1:3 ! ephone 4 device-security-mode none mac-address 0060.4710.AE01 type 7960 button 1:4 ! ephone 5 device-security-mode none mac-address 000C.8521.0C20 type 7960 button 1:5 ! ephone 6 device-security-mode none mac-address 00D0.D31A.7EE9 type CIPC button 1:6
Call routing configuration between CME routers
Dial peers are used to identify call source and destination endpoints and to define the characteristics applied between two CME routers. The destination pattern, configured in a dial peer by using the destination-pattern command, associates a dialed string with a specific telephony device. If the dialed string matches the destination pattern, the call is routed to the remote dial peers. You have to configure a destination pattern for each voice-network dial peer that you define on your network routers.
The destination pattern can be either a complete telephone number or a partial telephone number with wildcard digits, represented by a period (.) character. Each "." represents a wildcard for an individual digit that the originating router expects to match. For example, if the destination pattern for a dial peer is defined as "555....", then any dialed string beginning with 555, plus at least four additional digits, matches this dial peer.
CME-3 dial-peer configuration
dial-peer voice 1 voip destination-pattern 1... session target ipv4:192.168.65.254 !
CME dial-peer configuration
dial-peer voice 2 voip destination-pattern 2... session target ipv4:192.168.69.254 !