dial tone

音标发音

The phone must be out of order if you can’t hear a dial tone.
如果听不到拨号音，电话一定是坏了。
I've been looking around for a "commercially supported cloud-based VOIP PBX that provides dial tone" for the past few weeks and I keep coming up empty on the SIP phones.
在过去的几周里，我四处在寻觅着一个“商业支撑下、基于云的并可提供拨号音的网络电话交换机”，而一直无法享用SIP电话。
Like many other developers with a history in telecom, I learned that when you build a telephone switch, regulations say it must provide dial tone in 40ms, a difficult requirement to achieve.
像许多常年混迹于电信行业中的开发人员一样，我所学习到的是，若实现一个电话交换，则一定要在40毫秒内发出拨号音，这是一个难以实现的需求。

The dial tone is that state of awareness of the divine that Buddy speaks of when he says- when he speaks of being with God before God said, "Let there be light."
拨号音是神学意识的体现,巴蒂曾提过，当他提到在上帝说,让光芒普照大地，这句话前就与上帝同在时说过“
耶鲁公开课 - 1945年后的美国小说课程节选

The Web site is gone, and phoning the group's New York office yields a dial tone.
FORBES: Endorsement Rap
If I timed it right, he'd only hear a dial tone and I would be safe.
ENGADGET: Growing up Geek: Philip Berne Alt
You then had to wait hours for a dial tone, and pay exorbitant charges.
ECONOMIST: Press freedom

a continuous sound that tells you that a phone is connected to the phone system and is ready to be used