Tā zài dà diànhuà.
他在打电话。
He is on the telephone.
Notes:
他(Tā): he
在(zài): be in process of
打电话(dà diànhuà): make a phone call
Example:
A:王力在哪里?
Wánɡ Lì zài nǎlǐ?
wher's Wang Li?
B:他在打电话。
Tā zài dà diànhuà.
He's on the phone.