我在这部电话上听不到拨号音。

I can't get a dial tone on this phone.

听到拨号音后，就可以拨号码了。

When you hear the dial tone, dial the number.

在某些电话网络中不发送拨号音。

A dial tone is not sent in some telephone networks.

当她第二次拨号时，才意识到没有拨号音。

It was only as she tried for the second time that she realized that there was no dialling tone.

找到一个基于云的网络电话路由器，该设备还提供拨号音。

Find a cloud based VOIP PBX out there that is commercially supported that provides dial tone.