Although optional for travelers, you should register your volunteering trip abroad with the federal government of your home country.
For example the“Smart Traveler Enrollment Program” (STEP) run by the US State Department allows US citizens to enter information about an upcoming trip abroad. You enter details such as your travel dates, destination(s), address abroad, emergency contact and more.
The State Department will then be better able to assist you abroad in an emergency. What kind of emergency? Natural disasters like an earthquake or tsunami; or, say, civil unrest following an election. Registering with STEP could also speed up the process of replacing your lost passport while abroad.
As an added service, STEP can also send you electronic updates on travel warnings, travel alerts and other information for the country you’ll be visiting.
Government websites for registering your trip abroad
US Citizens: https://step.state.gov/step
UK Citizens: http://www.fco.gov.uk/en
Canadian Citizens: http://www.voyage.gc.ca
Australian Citizens: http://www.orao.dfat.gov.au
French Citizens: http://www.diplomatie.gouv.fr/en
South Africans: http://www.dfa.gov.za/consular/travel_advice.htm