在最佳变形条件下利用该钢进行精密塑料电话机按键模的超塑成形，可一次成形出精度较高的模具，证明其有较好的应用效果。
The superplastic forming of the precision plastics telephone key die can be realized in optimum conditions. The results show that the technology has good practical effect.
为了使电力系统通信设备的呼叫装置更加使用方便工作可靠，我们研制了以按键电话机发出双音频呼叫信号进行选择接收的音频选号装置。
In order to improve the ringing method of telephone used in power systems, a type of selective calling device using audio frequency has been developed.
当电话机没有“接通”时，各种线路按钮激活自动将第一根线路置于保留状态，不需要使用特殊的“保留”按键。
As long as a phone does not go "on-hook," activation of various line pushbuttons will automatically place the first line on hold without the use of a special "hold" button.
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