Welcome, Stein is on the phone, or this is Stein speaking.

 Empfang  is a greeting words, means ‘welcome’ or something like, I’ve received your line, and  Stein  is the call taker name, followed by  am Apparat  means ‘on the phone’, so the whole sentence is a general greeting way for call taker, with name and waiting for the caller to say something.

Hello, This is Peach, What is the telephone number for Mrs.Mazanke, Marketing department.

 hier  means ‘here’, like here is ‘Paech’or this is ‘Paech’ or my name is ‘Paech’ and  von  means ‘for’,  Frau  is ‘Mrs.’  Herr  is ‘Mr.’

One moment, 6834, and the direct line is 4817

I think, here, the 4817 means the extension number for internal dialing. Durchwahl  literally means ‘Direct Dialing’ here.

Thank you very much!
 schön  literally means ‘nice’, here with  Danke  means ‘very much’

Hello, I need the telephone number for Mr. Feldmeier in Munich
 brauche means ‘need’

Yes, the Area code number is 089 and then 448039087.
 Vorwahl means the ‘Area code’ for telephone number, don’t be mixed up with  Durchwahl ,  dann  means ‘then’

Stein,Welcome.

Good morning, Mrs. Stein, What is the telephone number for Mrs. Rosenberg in Dresden.

Mrs.Rosenberg. Service team?

Yes.

It is 264251 and 0351 for Dresden

You should be aware, the Dresden is a name of a place, 0351 for the place implies that the 0351 is a  Vorwahl 

We want to pay,please
 möchten means ‘want’,  zahlen  means ‘to pay’, actually the nouns for bill is  Rechnung 

Together or separated?
Here the waiter would check if they want to pay as a whole or go dutch (split the bill)

Together

2 Tea, this brings about 6 Euro.
 macht is a versatile verb, it is related to ‘do’ something. like  Was machst du?  means “what do you do (for a living)” . Here, just think it means ‘cost’

Here, please
it is more like “here you are”

Thanks

See you again
 Auf  here is just ‘upon’ like words, no real meaning here , just with the  Wiedersehen  This way of “good bye” doesn’t refer to the detail time for the next time meeting, it just mean “hopefully,probably, we can meet each other again”

Here is some difference of “goodbye”
 Bis gleich!  see you a moment later, very soon, in minutes.
 Bis Später!  see you soon, very soon, but may be in hours.
 Bis Morgen!  see you tomorrow, literally means next morning
 Bis Bald!  see you soon, could be day or weeks.
 Tschüss  bye, this simplest way.
 Auf Wiedersehen  more formal way of good bye. or see you again. not time implication.