Cisco Unified Communications Manager (CUCM)

Video #2: Region

Topics

• What is CUCM Region?• Brief introduction to Codecs• Common Codecs – G.711, G.729 and

iLBC• Region Configuration Steps

CUCM Region

• Defines the maximum bit rate between group of IP Phones.

• Codecs that have higher bit rate than the value set in Region will not be used between IP Phones.

• Region is used to for bandwidth sizing.• Codecs will determine how many calls are

possible for a given bandwidth.

Codecs

• The word CODEC is taken from the words COder and DECoder.

• Codecs are used for compression and decompression of audio signals.

• Not all audio codecs can be used for telephony.• IP Phones need to have the same Codec to play the audio

stream both ways. If IP Phones don’t have the same type of codec a Transcoder is required.– Traditional Transcoding: G.711 <-> Other– Universal Transcoding : Other <-> Other

• Some codecs are not free to use.• Most common codecs for telephony are already available in

the Cisco IP Phones.

Common CodecsCodec Information Bandwidth Calculations

Codec & Bit Rate (Kbps)

Codec Sample Size (Bytes)

Codec Sample Interval (ms)

Mean Opinion Score (MOS)

Voice Payload Size (Bytes)

Voice Payload Size (ms)

Packets Per Second (PPS)

Bandwidth MP or FRF.12 (Kbps)

Bandwidth w/cRTP MP or FRF.12 (Kbps)

Bandwidth Ethernet (Kbps)

G.711 (64 Kbps)

80 Bytes 10 ms 4.1 160 Bytes 20 ms 50 82.8 Kbps 67.6 Kbps 87.2 Kbps

G.729 (8 Kbps)

10 Bytes 10 ms 3.92 20 Bytes 20 ms 50 26.8 Kbps 11.6 Kbps 31.2 Kbps

G.723.1 (6.3 Kbps)

24 Bytes 30 ms 3.9 24 Bytes 30 ms 33.3 18.9 Kbps 8.8 Kbps 21.9 Kbps

G.723.1 (5.3 Kbps)

20 Bytes 30 ms 3.8 20 Bytes 30 ms 33.3 17.9 Kbps 7.7 Kbps 20.8 Kbps

G.726 (32 Kbps)

20 Bytes 5 ms 3.85 80 Bytes 20 ms 50 50.8 Kbps 35.6 Kbps 55.2 Kbps

G.726 (24 Kbps)

15 Bytes 5 ms 60 Bytes 20 ms 50 42.8 Kbps 27.6 Kbps 47.2 Kbps

G.728 (16 Kbps)

10 Bytes 5 ms 3.61 60 Bytes 30 ms 33.3 28.5 Kbps 18.4 Kbps 31.5 Kbps

G722_64k(64 Kbps)

80 Bytes 10 ms 4.13 160 Bytes 20 ms 50 82.8 Kbps 67.6Kbps 87.2 Kbps

ilbc_mode_20(15.2Kbps)

38 Bytes 20 ms NA 38 Bytes 20 ms 50 34.0Kbps 18.8 Kbps 38.4Kbps

ilbc_mode_30(13.33Kbps)

50 Bytes 30 ms NA 50 Bytes 30 ms 33.3 25.867 Kbps 15.73Kbps 28.8 Kbps

G.711

• ITU-T standard. Used in the PSTN (Public Switched Telephony Network and most IP PBX implementations.

• Comes in two variants – u-law and a-law.• U-law is commonly used in the United

States, North America and Japan. A-law is used anywhere else.

• Medium complexity codec – uses less computational resources.

G.729

• Mostly used in VOIP applications due to low bandwidth requirements.

• Commonly used for calls outside the IP LAN environment.

• Good for Latin Based language but not fit for music on hold.

• Has several two main variants of the original – G.729a and G.729b.– G.729a, medium complexity– G.729b, added VAD (Voice Activity Detection).

iLBC

• Internet Low Bitrate Codec – released in 2004.

• Was used in Yahoo Messenger, Gtalk and older versions of Skype.

• Royalty free – no need to pay to use.

Region Configuration

• Specify Region Name.• Modify Relationship to Other Regions.

– Set Max Audio Bit Rate– Set Max Video Call Bit Rate– Set Link Loss Type

• “Use System Default” will follow the values set in Service Parameter Configuration -> Cisco Call Manager.