The specific channel to use for SIRENE communications is the communication infrastructure for the Schengen environment (SISNET)33. Only if this channel is not available, shall another, and given the circumstances the most appropriate, means of communication be determined on a case-by-case basis, according to technical possibilities and the security and quality requirements that the communication has to meet.

Written messages are divided into two categories: free text and standard forms. The latter shall respect the instructions set out in Annex 5. The B34, C35 and D36 forms shall not be used any longer and are removed from Annex 5.

In order to achieve utmost efficiency in bilateral communication between SIRENE staff, a language familiar to both parties shall be used.

The SIRENE bureau shall answer all requests for information made by the other Member States via their SIRENE bureaux as soon as possible. In any event, a response shall be given within 12 hours. See also Section 2.16 on indication of urgency in SIRENE forms.

Priorities in daily work shall be based on the type of the alert and the importance of the case.