In current society, the deployment of distributed applications necessitates the development of trustable human recognition mechanisms that could be executed through open networks. If the recognition mechanism to be used is based on biometrics, then the biometric solution shall be developed as a network-based service. Additionally, as the biometric service will be executed by applications around the globe, it will be recommended to use standardised technology. This work shows the current standards in this area, as well as some of the gaps still existing. A solution for one of these gaps has been developed by the authors and is explained in the last section of this study. With the current definitions and reference implementations, the industry could implement network-based biometric services in an interoperable way.