One of the first things you might want to do in order to make your life in Bonn better is to find out how one can make the international telephone calls  cheaper. 
     Naturally, there are two possibilities to make international calls - using Deutsche Telecom  Card Phones or from your private phone in the room (I do not count mobile phones - I have no idea how one can make international calls cheaper in this case). 

     Normal Deutsche Telecom prices for card telephones are quite high. (They explain this that they have to maintain all these telephones, repair them....therefore they need money for this...) You have to buy a phone card (DM 6, 12 or 50) and, in principle,  you can call even now!.. Fortunately, there is (but, alas, only one in Deutschland) an operator "KomServ" - that can make your telephone calls from the usual card phones (to some countries) considerably cheaper. The rest of information how to make calls and prices of KomServ are here. 

     I do not mention here other operators  - because in all other cases you are supposed to buy an additional phone card of this company (you have to find the place where you can buy it first - it takes also time!) You can find more info about them here.

    The other possibility is to install the telephone in your room. All this procedure may take about one week. You have to go to any T-Punkt and fill out the necessary paper. First of all it is reasonable to find out whether the previous person who lived in your room had a telephone (it makes things easier, cheaper and faster). You will need this telephone number (or at least his/her name) during the filling in the application for you phone (you can do it in any T-Punkt). If you found out this number - the installation will cost you about DM 50. If not -  DM 50 + DM 50. And DM 25 every month.

    In one week you can make international phone calls (that are considerably cheaper then ones from the card phones)! But there is the way to make them even cheaper - using the "Sparvorwahl". This is the number you  have to dial before you dial your "normal international number".  And prices are really lower - for example I found  how to call to USA only for DM 0.09. Just to compare - a telephone calls to any city in Germany costs about DM 0.03-0.12 . The rest information about prices and "Vorwahl"-s you can find here.

     And one more point about the private phones. You may find out later on that there is a "Sozialanschluss"  - the way how students may reduce the monthly fee from DM 25 to DM 9. You can apply for this feature. But if you are planning to make a lot of international calls using not Deuthcshe Telecom prices but using these "Sparvorwahl"-s, this system ceases to work properly. Deutsche Telecom in this case does not wont to decrease your monthly fee by these DM 15, but only by a couple of marks - that makes this system quite useless... So it is up to ypu to decide whether to apply or not - this is free but lots of papers to fill in - your time...