+62 856, 857, 858 and 815 numbers: Indosat IM3 mobile lines

A number starting +62 815, 816, 855, 856, 857 or 858 is an Indonesian mobile number from Indosat, sold under the IM3 brand and run by Indosat Ooredoo Hutchison. Indonesia has no mobile number portability, so the prefix still identifies the operator, but not the person or their city.

Indonesia · Mobile numbers · Facts checked November 9, 2026

What these numbers look like

From abroad: +62 856 XXXX XXXX
Inside Indonesia: 0856-XXXX-XXXX

Drop the leading 0 when dialling from abroad. Indosat numbers come in different lengths, so length alone tells you nothing about whether a number is genuine.

Who uses Indosat (+62 815, 816, 855-858) numbers?

Komdigi (Indonesia's Ministry of Communication and Digital Affairs, formerly Kominfo) allocates mobile number blocks to operators. The government portal Indonesia Baik lists 0815, 0816, 0857 and 0858 under Indosat's former Mentari brand and 0856 under IM3; Indosat sells new 0856 and 0857 numbers in its own IM3 shop, and its official IM3 WhatsApp account uses an 0855 number. Whatever the original brand, all six prefixes are Indosat numbers today. On 4 January 2022 Indosat merged with Hutchison 3 Indonesia (the Tri brand) to form PT Indosat Ooredoo Hutchison Tbk; both IM3 and Tri numbers now belong to the same company. 0857 has its own page with more detail.

Prefix	Operator	Note
0855, 0856, 0857, 0858	Indosat (IM3)	Mixed former IM3, Mentari and Matrix ranges
0815, 0816	Indosat (IM3)	Former Mentari / Matrix range
0895-0899	Tri (3), Indosat Ooredoo Hutchison	Same company since 2022; see the Tri page

Who is calling you from a Indosat (+62 815, 816, 855-858) number?

Most +62 856 and 857 contacts are ordinary Indosat customers. IM3 is a popular prepaid brand with students and younger users in Java, so you will see these numbers in marketplace chats, delivery updates and family WhatsApp groups. Unsolicited WhatsApp messages from abroad offering part-time work or sending files are the main red flag, regardless of prefix.

+62 857 numbers: who is calling from Indosat 0857

Scams seen with Indosat (+62 815, 816, 855-858) numbers

Part-time job task scams: OJK's Satgas PASTI described scammers who pay a small reward for liking and subscribing to social media posts, move victims into a group chat, then demand deposits for larger tasks and vanish (February 2024 warning).
Courier and invitation APK files: Komdigi documented WhatsApp messages impersonating package couriers and sending 'digital wedding invitations' or election documents as .apk files. Installing them gives attackers access to SMS one-time passwords and mobile banking.

What to do about a call from Indosat (+62 815, 816, 855-858)

Never install an .apk file received over WhatsApp.
Report the number at aduannomor.id (Komdigi). Verified numbers are forwarded to the operator for blocking within 24 hours.
If you lost money, file a report with the Indonesia Anti-Scam Centre at iasc.ojk.go.id; check suspicious bank accounts at cekrekening.id.
Call OJK on 157 to check whether a company offering jobs or investments is licensed.
Block and report the chat in WhatsApp.

Check the exact number

A series tells you what kind of line called. To check the full number you got, use these free tools:

Phone number validator: which country, mobile or landline, and whether the length is right.
Spam number checker: warning signs that a caller is a scammer.
Who called me? Reverse phone lookup: what the number tells you about the caller.
Indonesia country code +62: full dialing guide and number formats.
Calling Indonesia from abroad: per-minute rates if you need to call someone there.

Frequently asked questions

What network is +62 857?

Indosat (IM3). It has its own page on this site with more detail on 0857 numbers.

Is 0858 still Mentari?

0858 was listed under the Mentari prepaid brand. Whatever the card name, an 0858 number is an Indosat number on the IM3 network.

Are Indosat and Tri the same company now?

Yes. Indosat and Hutchison 3 Indonesia merged on 4 January 2022 to form Indosat Ooredoo Hutchison. IM3 and Tri still keep their own prefixes.

Could a +62 856 number have switched to Telkomsel or XL?

No. Indonesia has not introduced mobile number portability, so the prefix still shows the current operator.

Sources

Numbering facts on this page come from the regulator or operator sources below, checked November 9, 2026. We never publish individual personal phone numbers.

Indonesia Baik (government portal) - Kenalan Sama Kode Prefix Kartu Seluler di Indonesia (indonesiabaik.id)
IM3 Shop (Indosat) - nomor cantik, 0856/0857 numbers on sale (im3shop.ioh.co.id)
IM3 Care - official IM3 WhatsApp 0855 number (care.im3.id)
CK Hutchison - Indosat and Hutchison 3 Indonesia merger completed, effective 4 January 2022 (ckh.com.hk)
detikInet - Menkomdigi on mobile number portability petition (15 Sep 2026) (inet.detik.com)
OJK - Satgas PASTI Blokir 311 Pinjol Ilegal dan Pinpri (13 Feb 2024) (ojk.go.id)
Komdigi - [HOAKS] Pesan WhatsApp Mengatasnamakan Kurir Pengiriman Paket (komdigi.go.id)
Komdigi - [HOAKS] Aplikasi Undangan Pernikahan Digital (komdigi.go.id)
InfoPublik - Kominfo Buka AduanNomor.id (15 Nov 2023) (infopublik.id)