We have installed an Online Ticket Booking System, so you can order all all the tickets electronical. Because ticketing is being conducted by the Zürich Tonhalle, there is a 10,-SFr charge for processing from their end.
If you feel more comfortable with phone and paper order, then you can contact one of the following addresses:

Zürcher Festspiele, Ticketoffice
c/o Tonhalle Zürich, Eingang T, Claridenstrasse 7, CH-8002 Zürich
Tel. +41 1 206 34 34, Fax +41 1 206 34 69

Zürcher Festspiele, Geschäftsstelle und Info-Office:
Postfach CH-8026 Zürich
Tel. +41 1 240 32 20, Fax +41 1 240 32 21
info-office@zuercher-festspiele.ch
http://www.zuercher-festspiele.ch/

Theaterhaus Gessnerallee, Gessnerallee 8
Tel. +41 1 225 81 11, Fax +41 1 225 81 20
Tickets sold for own performances only

Schauspielhaus, Rämistrasse 34
Tel. +41 1 265 58 58, Fax +41 1 265 57 04
Tickets sold for own performances only

BernhardTheater, Theaterplaz 1
Tel. +41 1 268 66 86, Fax +41 1 268 66 93
Tickets sold for own performances only


Other ticket offices:

BIZZ, Bahnhofstrasse 9, Tel. +41 1 221 22 83
Jelmoli Zürich-City, Seidengasse 1, Tel. +41 1 220 44 66
Jecklin Musikhaus, Rämistr. 30, Tel. +41 1 253 76 76
Musik Hug, Limmatquai 28, Tel. +41 1 269 41 00

Generally the booking conditions of each organiser apply.
All information subject to change.