A calling visa is a requirement for some nationalities prior to entering Indonesia using another visa, i.e., VOA or Tourist visa.

Passport holders from the following countries must obtain reference from the Directorate General of Immigration in Jakarta before applying for an Indonesian visa:

1. Afganishtan
2. Cameroon
3. Guinea
4. Israel
5. North Korea
6. Liberia
7. Niger
8. Nigeria
9. Pakistan
10. Somalia

Representative offices of the Republic of Indonesia may issue a visa with their own power (without the approval of the Director General of Immigration) for citizens of Calling Visa countries who have a permanent residency card in a country outside their home country, for participating in:

• conference or training programs conducted by government agencies and / or international organization under the United Nations
• investment activity in Indonesia
• business discussions
• socio-cultural activities

these visas can be issued if:

• if the applican’ts country doesn’t have an Indoensian embassy
• The applicant is a professor, teacher, student, Expert, Investor, or Manager (and their family members).

Recipients can be

Requirements:

• Fill out the correct form
• Sponsor needs to be an Indonesian citizen, a person residing in Indonesia, or a company legally established in Indonesia.
• Invitation letter from the sponsor in Indonesia should be addressed to the Immigration Department of the Embassy of the Republic of Indonesia.
• Copy of the sponsor’s ID (KTP).
• Confirmation letter from the sponsor in Indonesia (organization or company) where the applicant is working or studying, addressed to the Immigration Department of the Embassy of the Republic of Indonesia.
• Marriage Certificate (if applying for spouse as well)
• Birth Certificate (of children)

Procedure:

1. Provide the requirements stated above.
2. Attend an initial interview.
3. Within a week, the embassy will issue a reference number for the applicants and sponsor.
4. The sponsor will need to get an approval letter from the Directorate General of Immigration in Jakarta.
5. Once you receive the approval Letter, you may process the visa at the Embassy of the Republic of Indonesia and pay the required telex fee.

Source : http://www.expat.or.id/info/docs.html#CallingVisa