Don't think about 'dark zone' and losing contact from where you are

The international country code for Indonesia is +62. The local area code for Yogyakarta is 274. There are three main telecommunication providers in Indonesia: Telkom Indonesia, Indosat and Excelcomindo. Coin operated public phones are limited in Yogyakarta. However there are many official telephone kiosks called Wartel.

International dialing
To make an IDD call from Indonesia, dial the access code 001 (for Indosat) and 007 (for Telkom), followed by the country code, area code and party's number. Also available cheaper IDD call via VoIP Technologies, IDD Prefix is 01016 (for Indosat user) and 01017 (for Wartel, Telkom, and Telkomsel user), and 01000 (for XL -excelcom- user)

Mobile Phones
Mobile Phones are carried by almost everyone in Indonesia. Prepaid SIM cards are widely available from many telecommunication providers, such as, Telkomsel, XL, Indosat, 3, and Axis, just bring your own GSM 900 or GSM 1800 phone. The pre-paid SIM card costs around Rp 10,000 up to Rp 30.000. A local phone call costs between Rp 500-Rp 2000 per minute. Local text message (SMS) costs about Rp 350, while international SMS cost about Rp 3000. Also available for CDMA users, Telkom Flexy, StarOne, Esia, And Mobile-8 which are cheaper, but you must have RUIM CDMA Phone

Internet Cafes
There are many internet cafes in Yogyakarta which offer speedy access to the internet. Several hotels provide Wi-Fi on the lobby. Ask the front desk about internet access. The Taman Sari food court at the Plaza Ambarrukmo, coloquially known as Amplas, offers a free wireless internet service for any Wi-Fi compatible device.

Tourism
Tourism Information Centre in Jogyakarta:

• Jalan Malioboro 56, 62 274 587 486, (fax: +62 274 565 437), 
• Tourism Promotion Board. Jalan Malioboro 16, +62 274 586809.
• Jalan Cendana 11, +62 274 562628, 564945 (fax: +62 274 564945).