AT&T公司的IP电话尝试又迈上了一个新的台阶,其已在旧金山开通可以进行州与州之间通话的IP电话服务。开通的AT&T的多级连接存储服务系统是在一个有限的服务器基础上延伸开来,这个系统采用了AT&T的IP主干网。官员们认为AT&T在自己的主干网上运行此服务系统,可以比在别的公共网络上运行获得更高的话音质量。IP电话在美国任何地方的花费是每分钟7.5美分,每个月的最低消费是2美元,但这个最低消费将在9月30日被取消。AT&T的话音传送速率可以与其它新近提供IP电话服务的公 AT & T’s IP phone trials have taken a new step toward opening an IP telephony service in San Francisco that allows state to state calls. The open AT & T multi-tiered storage service extends from a limited server that uses AT & T’s IP backbone. Officials think AT & T runs the service on its own backbone and can get higher voice quality than running on other public networks. IP phones cost anywhere from 7.5 cents per minute anywhere in the United States to a minimum of $ 2 a month, but the minimum charge will be canceled on September 30. AT & T’s voice transfer rate can be used with other public IP telephony services