My mobile phone is extremely useful.

我的手机极为有用。

《柯林斯英汉双解大词典》

If you call my mobile, you get me.

如果你打我的手机，就能找到我。

youdao

My mobile phone is helpful.

我的手机很有用。

youdao

If it can display information off my mobile phone, too, all the better.

FORBES: Why I Would Buy Google Glass But Not an iWatch

It immediately started downloading an .apk and my mobile antivirus popped up, saying: THIS IS A TROJAN.

FORBES: Mobile Antivirus: Don't Think About It, Just Be Sure It's There

Which brings me to month 3 of dumping my mobile, the time machine that used to reside in my pocket.

FORBES: Dumping My Mobile 3 - Rediscovering Timeless Moments