"My telephone is there."
Not exactly, but it would be somehow weird to start with "hunak" (unless maybe in some form of poetry!) - but a regular (typical) order would be (هاتفي هناك).
Saying this though, it is about which one of the two words you want to bring attention to first: Is it your phone? or the place where your phone is? Whichever you want to bring the attention to as the important part of the phrase, put it first. If I asked you (where is your phone), well, both orders can work and the meaning will be delivered to the receiver (me).
I'm not sure if Duolingo is using "telephone" in other questions but anyway, "Haatif" is the more accurate Arabic term for it. This said, Telephone is used in daily speech in dialects and even can get through in texts written (supposedly) in standard Arabic.
The word "Haatif" هاتف comers from the verb هتف (hatafa), meaning to call/yell from afar.
هاتف جوال is indeed (mobile phone)
However, this name is not quite standardized (it is used in some areas in the Arab world, specifically the Gulf region but other places have other names).
The proper name for Mobile Phone in standard Arabic would be هاتف محمول (meaning: carried-phone).
All in all, the English "telephone" is typically translated as هاتف only.