As getting a fixed line remains an unaffordable luxury for many Indonesians, wartel (short for warung telekomunikasi) can be found on most every street in Indonesia.

If you have Global System Mobile (GSM) cellular phone, ask your local provider about "roaming agreement/facility" with local GSM operators in Indonesia (ie: PT Indosat, PT Telkomsel, PT Excelindo etc).

Making local calls: Dial (telephone number)

Making long distance calls: Dial 0-(area code)-(telephone number)

Making international calls: Dial 017-(country code)-(area code, if any)-(telephone number)

Beside "017" prefix, you can use "001", "007" or "008". For example: 001-(country code)-(area code, if any)-(telephone number)

You can make International calls through operator: dial 101 or 102.

Making long distance collect calls: Dial 0871-(area code)

Connecting to the Internet: Dial 080989999 (from your modem), costing you Rp. 165/minute in business days and Rp. 100/minute in Saturdays and Sundays

TELKOM Calling Card access number: Dial 168

Emergency

Here is a list of emergency numbers in Indonesia (please note that while these numbers are accessible for free from all non-mobile telephones, they may not be accessible from mobile phones [for mobile phones, you'd better use international mobile phones emergency number, 112]) :

Police : 110
Fire department : 113
Ambulance : 118
Search and rescue team: 115.
Indonesian Police HQ. Jl. Trunojoyo 3, South Jakarta. Tel.: (62)(21) 7218144.
National Search and Rescue agency (BASARNAS): Jl. Medan Merdeka Timur No.5, Jakarta 10110. Tel.: (62)(21) 348-32881, (62)(21) 348-32908, (62)(21) 348-32869, Fax.: (62)(21) 348-32884, (62)(21) 348-32885.

Mobile phones

The Indonesian mobile phone market is heavily competed and prices are low: you can pick up a prepaid SIM card for less than Rp 20,000 and calls may cost as little as Rp 1,000 a minute (subject to the usual host of restrictions). Indonesia is also the world's largest market for used phones and basic models start from Rp 250,000. The largest operators are Telkomsel (brand simPATI), Indosat (brands Matrix, Mentari, IM3) and Excelcomindo (brands Jempol, Bebas).

If you have Global System Mobile (GSM) cellular phone, ask your local GSM operator about "roaming agreement/facility" in Indonesia. Most GSM operators in Indonesia have roaming agreement with various GSM operators worldwide. Using roaming facility, you can use your own cellular phone and GSM SIM card in Indonesia.

Most Indonesian operators use GSM, but beware of the few offering CDMA phones: they are slightly cheaper, but generally not usable outside major cities. Be sure to double-check when buying!

Internet

The modern-day version of the wartel is the warnet, which feature Internet-connected PCs as well, and many shops now do double duty. Prices vary considerably, and as usual you tend to get what you pay for, but you'll usually be looking at around Rp 5,000 per hour. In large cities, there are free hotspot on certain shopping malls, McDonald restaurants and StarBucks cafes. Some hotels provide free hotspot on the lobby.

If you have GSM/WCDMA Mobile phones, you can just easily use them for internet connection with prepaid card from Indosat called Mentari or IM3. There is a GPRS package with time-based calculation like PSTN dialup. The charge is only Rp 110 per minute or Rp 6600 per hour. Mentari or IM3 starter-kit is Rp 10,000 with vouchers Rp 25,000, Rp 50,000 or Rp 100,000