The Auxilium 10-digit number system holds the phone numbers of the next of kin, as well as patient records.
Bosses hope people will sign up to the scheme, which allows 999 staff to relay the information from a database to paramedics.
About 500,000 numbers - which will cost Â£1 - are being donated to charities.
Abingdon-based inventor Grant Moreton came up with the idea for the system after two pupils from his school died in separate road accidents.
He said: "[The system] is just to get access to paramedics as soon as possible and get in touch with the parents as soon as possible."
South Central Ambulance Service (SCAS), which covers Berkshire, Buckinghamshire, Hampshire and Oxfordshire, has launched a trial of the new system.
Director of operations Luci Stephens said: "There are occasions when it would be incredibly useful to have key details about a patient which they might not be able to provide to us due to their medical condition."
The 10-digit number can be put on bike helmets, key rings, and bracelets.
People in the Thames Valley have to register for the Â£1 service, but the database is free to all schoolchildren and 500,000 numbers are being donated to charities.
Ambulance services in the South of England have begun using a new ID number system for patients that holds vital medical information.