Analog phones connected to PSTN typically use _______ signal type.
What issue does ground start nullify?
What is a PBX?
Private Branch Exchange
Give example of supervisory signaling.
On hook, off hook, ringing,
Give example of informational signaling.
dial tone, busy, ringback
Dual Tone Multi-Frequency
Time Division Multiplexing - allows networks to carry multiple conversations on a digitized line.
Channel Associated Signaling- Signaling is sent using same BW as voice.
uses 8th bit of every 6th frame.
Common Channel Signaling
Signaling transmitted using separate dedicated channel.
- timeslot 24 for T1 line (channel 23)
- timeslot 17 for E1 line (channel 16)
- 24 seperate 64-kbps channels
- 30 seperate 64-kbps channels
- Each channel is known is as a DS0 (digital signal 0)
Name 6 pieces of the PSTN
- Analog telephone
- Local loop
- CO switch
- Private switch
- Digital telephone
- Numbering plan designation.
- North American Numbering Plan
What freq range did Nyquist want for voice reproduction?
How many samples per second?
- 300-4000 hz
- sampled at 8000 times a second
- 8 bits of data * 8000 = 64000 (64 kbps)
what are the 2 main codecs used?
- G.729 8 KBPS
- G.711 ulaw 64 KBPS
- (ulaw = North America and Japan)
Real Time Transport Protocol (Even port numbers)
Real Time Control Protocol port = odd one up from RTP port
example: RTP port 17,654 RTCP port 17,655
How large is a t-1 frame sent over a digital CAS connection?
What are the 2 main protocols for endpoint connectivity from the CME?
- SIP (SIP is a bigger file)
- SIP is becoming the standard
What is CCP?
Cisco Configuration Professional
Describe 7 key features of CUCM.
- Full support for Audio and Video
- Appliance based (Linux)
- Redundant server cluster (up to 30,000 phones, 8 subscribers and 1 publisher per cluster)
- Intercluster and voice GW control
- Disaster Recovery System (DRS)
- VMWare support
- Directory support (LDAP)
Describe CUCM cluster DB relationship.
- Publisher holds master writeable DB. Subscribers hold non-writeable copies of the DB.
- If publisher dies, Subscriber can serve phones but can't make changes to the DB.
Describe parameters for small environment
and max devices.
- 500 phones or less - One appliance, Publisher and subscriber as one. Over that, split out publisher from call processing and put it on a subscriber (up to 8 subs).
- Above 1250, put TFTP server on dedicated server.
Describe CUCM subscriber role as primary server.
Primary server is the first one (as defined) that an IP phone contacts to register with. 1,2,3 in order and start again. Don't confuse the primary server with the publisher.
How many mailboxes can the Cisco Unity Connection (CUC) support?
- 20,000 and 20,000 with two servers in a active/active role.
Detail flow of a call from PSTN and ending up on CUC via CUCM.
- Call in from PSTN, dial plan sends call to CUCM
- CUCM routes call to Phone via SCCP or SIP
- phone no answer
- CUCM uses SCCP or SIP to send call to CUC
- CUC recognizes extension (DN) and connects to correct mailbox
- Cisco Unified Presence
- Cisco unified Personal Communicator (aka softphone)
- Real-time Transfer Protocol
- Voice Profile for Internet Mail
- Digital Signal Processor
- Cisco Unity Express (module for CME for voicemail, 450 max)
- Interactive Voice Response
- InterCluster Communication Signaling
What are power methods for an IP phone?
POE, Brick and Powered patch panel.
describe a VLAN.
- IP Subnet
- Broadcast domain
What is the trunking protocol?
What mode on port supports IP and vlan connectivity.
- switchport mode access
- switchport access vlan 10
- switchport voice vlan 20
- Verify: sh vlan bri
a. How does the ip phone send data from a device to the switch?
b. How does the ip phone send voice to the switch?
Tagged or Untagged.
a. untagged (switch does the vlan tagging)
b. tagged (voice vlan learned from switch upon bootup via CDP)
What cmd forwards DHCP requests to different LAN/VLAN in router?
ip helper-address *x.x.x.x*
What DHCP option supplies IP phone with TFTP IP address?
What is the best NTP stratum number?
- Stratum 0
- (Stratum 0-4 are the options, each layer learns the time from a device in the layer above it)
What 2 protocols can be used for IP Phone registration?
Depends on phone firmware. SIP is fast becoming the most preferred.
Voice VLANS are not really trunks, how would you portray them?
Access ports that support tagged voice VLAN data.
How does spanning-tree portfast help IP phone boot-up process?
Phone starts looking for DHCP server right away, and without the spaning-tree portfast command, switch goes into STP process and does not open the port for about 53 seconds.
What file does the phone ask for from the TFTP server.
What file does it get if no file is found?(default).
default is XMLDefault.cnf.xml