电话断线 ：drop call

手机没电了

My phone is dead

The battery of my mobile phone is dead

没信号：

no signal

信号不好：

spotty service

流量：

data

I'm out of data

其他常用表达

Can you hear me clearly？

Text me.

I often turn off my cellphone when I have a meeting.

His cellphone is busy now.

I forgot to recharge the battery.

I forgot to take the mobile charger.

I turned off my phone.

这些表达涵盖了手机使用中常见的情况和需求，希望对你有所帮助。