The reason for these designs is that if the compression of voice channels is done at the site of the MSC, the number of fixed transmission links between the BSS and MSC can be reduced, decreasing network infrastructure costs.
这些设计的原因是，如果对语音信道的压缩工作被在MSC的站点完成，那么在BSS和MSC之间的固定传输链路就可以减少，从而降低了网络基础设施的代价。