Pick up the phone
How would you say in German the following phrases:

— Pick up the phone! It is ringing already 10 minutes!
— Could you answer the phone, I'm a little busy at the moment.
— This is useless to call them. They never answer the phone.

In Russian there is a construction, that could be literally translated as "come to a phone", which means "answer tthe phone". Do we have something similar in German?

Also in German there is a word "das Apparat" (— Wer ist beim Apparat?). How could one use this word and especially in the previous contexts.

Thanks!

Question

Pick up the phone
How would you say in German the following phrases:

— Pick up the phone! It is ringing already 10 minutes!
— Could you answer the phone, I'm a little busy at the moment.
— This is useless to call them. They never answer the phone.

In Russian there is a construction, that could be literally translated as "come to a phone", which means "answer tthe phone". Do we have something similar in German?

Also in German there is a word "das Apparat" (— Wer ist beim Apparat?). How could one use this word and especially in the previous contexts.

Thanks!

Answer

Nimm den Hörer ab. Es (/Das Telefon) klingelt schon (/bereits) seit 10 Minuten!

Kannst du das Gespräch (an)nehmen (/Kannst du rangehen)? Ich bin gerade (ein bisschen) beschäftigt.

Es hat (/macht) keinen Sinn (/Es ist sinnlos), sie anzurufen. Sie gehen nie ran (/Sie heben nie ab).

"den Hörer abnehmen" (to pick up the receiver)
"ans Telefon gehen" (to go to the phone)
"das Gespräch annehmen" (to answer the call)
"es ist niemand dran" (daran, am Apparat/am Telefon)

"Wer ist am(!) Apparat?" (der Apparat /das Gerät)

Answer

...ans Apparat rangehen. = come/go to the phone
Apparat = apparatus and is any kind of mechanical contraption.
ran, = either heran or hinan. 
raus = either heraus or hinaus.
Both ran and raus are colloquial.

Answer

In casual language the verb "rangehen" is almost always used. The "ran" is a shortend form of "heran". 
The verb means in a situation when the phone is ringing "to answer the telephone".

Gehst du bitte mal endlich ran? Es klingelt schon seit 10 Minuten. 
Kannst du bitte rangehen? Ich bin gerade beschäftigt.

The construction used almost as often is "ans Telefon gehen", followed by "das Gespräch annehmen" which is already kind of formal, possibly used in an office.
I never heard anyone say "den Hörer abnehmen" in a situation in which the telephone is ringing. If someone tells you "Kannst du bitte den Hörer abnehmen." it somehow sounds as if the person is really getting impatient because he or she is kind of explaining to you how one is to answer a call.