Israel has many good quality companies providing telephone services. You can purchase a SIM card with credits or a line with monthly payments. According to the experience of the Post-docs questioned about it, Golan is recommended as you do not need an Israeli ID, just your passport and a credit card. Besides, they offer good deals for internet and some of their plans include unlimited calls also to landlines of 56 different countries.
The Edmond J. Safra Campus has password free Wi-Fi at the HUJI-Guest network.