This paper proposes to benefit from each natural network authentication procedure provided by operators to allow mutual authentication between two multi-capacity devices and guarantee the same security level to both of them. Operators can agree providing jointly this authentication service so multi-operator crossed authentication infrastructures can take place for instance over internet. As such, users needing strongly secure interconnectivity (e.g. SIP usage or over ad hoc infrastructures) can access to this service through Internet with no huge extra costs contrary to PKI or Kerberos solutions. Additionally to this attractive marketing offer, authentication could become a new growth for operators