送交者: steven 于 2004-12-30, 21:53:21:
回答: great! thanks, so 由 enable 于 2004-12-30, 18:40:29:
need the SS7 signaling path which is expensive to develop and maintain. Once migrated to VoIP, there is no need to SS7. For the well developed countries like the US, Europe or Japan, SS7 has been well established, but adding new features still cost. The phone line goes into individual household in the US can deliever over 1.5Mbps line speed, however, that is not where the VoIP takes place. Currently most corperates use VoIP because one, they have already leased lines, and it is a cheaper solution especially for long distance. Because when you call long-d, you may need to jump to a different providers's networks and that's expensive. However, for VoIP, it is not the case, jumping to a different network is the whole design goal for IP.
Look at VoIP from wiki and you will learn something new.