Learn Portuguese (Portugal): O telemóvel está aí.

In Portuguese, aí specifically means "there where you are" or near the listener. If the phone was further away from both the speaker and the listener, you would use ali or lá.

Why do we use está instead of é for "is"?

The verb estar is used to describe locations, among other temporary states. Since a mobile phone is a movable object and we are pointing out its current physical location, we must use está rather than ser.

Is telemóvel the only word for "mobile phone"?

In Portugal, yes! The word telemóvel is the standard European Portuguese term. If you ever watch Brazilian content or use other language apps, you might see celular, but in Portugal it is always telemóvel.