MOS tab
The MOS tab allows you to specify which sources of delay are used in MOS score calculations, and it allows you to configure your E-Model parameters if its defaults do not suffice. This tab becomes especially important for tracking the performance and clarity of VoIP calls.
 
See Table 25 for a list of noteworthy settings.
If you are using a VoIP codec that Observer does not recognize by default, change the value of the E-Model parameter impairment for unrecognized codecs to the appropriate value shown in Table 26.
The E-model based on conditions, equipment, and expectations at your site. Some of the values (Send and Receive Loudness Ratings, for example) are functions of your phone specifications. Others (Room Noise levels, for example), are functions of ambient conditions at your site. Typically, the default values should work fine. To fine-tune the E-model to exactly match the conditions at any particular site is an involved process that requires test equipment and a thorough understanding of the E-model. See the ITU G.107 specification for a more detailed discussion of the E-model.
Tip! The default settings in the MOS tab do not need to be changed unless there is reason for doing so—the defaults work well for many VoIP networks!
Table 25. MOS settings
Setting(s)
Description
MOS score network delay
These settings tell Observer which source of delay should be used in MOS calculations; the first found source of delay is used, and the items at the top of the list take precedence over lower items.
E-Model parameters
These settings allow you to customize your E-Model parameters. The E-Model parameters have a direct effect on how your MOS score is determined. We recommend leaving these at their default values until you have reason to change them.
If you are using a VoIP codec that Observer does not recognize by default, change the value of the E-Model parameter impairment for unrecognized codecs to the appropriate value shown in Table 26.
Defaults button
Clicking the Defaults button will restore the E Model parameters to their original values. This button does not affect the MOS score network delay settings.
Table 26. Codecs
If you use this codec
Use this value…
G.711
7
1016 8K
17
G.721
7
G.723
17
DVI4 8K
17
DVI4 16K
17
G.722
17
16 Bit Linear (2 Channel)
17
16 Bit Linear (1 Channel)
17
QCELP 8K
21
MPA 90K
17
G.728 8K
13
DVI4 11K
17
DVI4 22K
17
G.729
15
G.711 (a-Law) 64K
7
G.711 (a-Law) 56K
17
G.711 (u-Law) 64K
7
G.711 (u-Law) 56K
17
G.722 56K
17
G.722 48K
17
G.722-1
17
G.722-2
17
G.723-1
17
G.723-1 Annex C
17
G.726-16
40
G.726-24
25
G.726-32
7
G.726-40
2
G.728
7
G.729
15
G.729 Annex A
20
G.729 Annex B
20
G.729 Annex A & B
20
G.729 Extensions
20
IS11172
11
IS13818
11
GSM Full Rate
20
GSM Half Rate
23
BV 16K
17
BV 32K
17
VBD
17
ILBC
17
Speex
17
IMA ADPCM
17
LPC10
17
Telephony Event
17
Audio Tone
17
G.711 (A-law) with PLP
17
G.711 (U-law) with PLP
17