I tried calling you on your mobile.
我试着打过你的手机。
A：I tried calling you on your mobile.
A：我试着打过你的手机。
B：What time was that?
B：什么时候?
A：It was about an hour ago. But I couldn’t get you.
A：大约1小时以前。但是不能和你联系上。
B：I was on the subway. I don’t think you can get a signal underground.
B：我在地铁上。我想地铁里没有信号。
There are various situations and reasons for not receiving a phone call.
有很多情形和原因不能接到电话。