Specifications
2-20
Reference Guide
Model No.
Running Head
ADPCM Voice Compression Server Applications
2.5.1 PBX to PBX Trunk Application
Figure 2-10 shows the IAD with an ADPCM server used to compress two T1 or E1
PBX-to-PBX trunks into a single trunk. The voice from each PBX is connected via a digital
T1 or E1 connection to the IAD. The voice channels are routed to the ADPCM server, where
each voice channel is compressed to 32 Kbps. The compressed voice is routed to the outbound
T1/E1 link to the other IAD unit, where it is decompressed and placed back into two T1 or E1
trunks to the remote PBX. PBX to PBX trunk lines can be compressed 2:1 to reduce leased
line charges. The application is also valid for analog PBXs and key systems.
Figure 2-10. IAD using ADPCM for PBX to PBX Application
2.5.2 Automatic Call Distribution Application
The ADPCM server can be used to reduce leased line charges in automatic call distribution or
remote call center applications by increasing the number of voice circuits supported on a
single T1 or E1.
The application shown in Figure 2-11 illustrates an ISDN-based automatic call distribution
system. The integrated access system is used to provision BRI remotely via BRITE (BRI
Terminal Extension). With the IAD, ten BRI circuits can be extended to remote locations over
a single T1 line, and 13 over a single E1 line. The IAD is able to do this by placing the 2B+D
signal into 2.25 time slots (1 for each B, and .25 (16Kbps) for the D channel).
The ADPCM server is used to increase the number of BRI circuits supported per T1 or E1 by
compressing the B channels in voice only applications. This means that a 2B+D channel can
be transported in 1.25 time slots (.5 for each B, and .25 for the D channel). Hence, 19 BRI
circuits (38 voice channels) are transported over a single T1 and 24 BRI circuits are
transported (48 voice channels) over a single E1.
PBX
T1/E1
T1/E1
IAD IAD
PBX
T1/E1 carrier
Network