1) Phones and Cell Phones
Public phones in Germany operate mostly by phone cards, which can be purchased in the amounts of five, 10 and 20 Euros at newsstands, bookstores and other small shops. The cheapest way to call home is by using a phone card from your major North American long distance carrier.
Note the following emergency numbers before leaving; they can be dialed from any public phone free of charge: 110 for the Police and 112 for the Fire Department and Emergency Services.
Cell phone coverage is almost 100% throughout Germany. However, frequencies throughout Europe differ from those used in North America. Your service provider can tell you if your phone is compatible with the German/European system, and offer you alternatives if it is not.
2) Internet
Bringing a laptop to Germany is simple: most now run on both 110 volts, as in North America, or 220 volts, as found throughout Europe. Although the voltage is universal, you will still need an adapter to plug your computer into an electrical outlet.
While in Germany, the internet is easily accessible. You can often log on from your hotel, either right from your room or in computer rooms and business centers which offer internet access to guests. If neither is available, ask for directions for an internet café. There is usually one in every neighborhood.
Sources:
http://www.visits-to-germany.com/index.html