Interdomain Trust-Relationships for SIP-based Roaming
snom technology AG
This draft describes an authentication mechanism which can be used to enable users of VoIP to globally roam between any number of ITSPs (Internet Telephony Service Providers) without needing to have a prior customer or billing relationship with all of them. This enables profiles and one- line-billing. Providers using this authentication mechanism do neither need full-mesh trust relationships or roaming agreements with every other possible provider nor do they need to rely on a centralized brokerage entity to process calls. The Home Network (HN), which handles all AAA for a user attempting to use an ITSP's service is determined through a unique identifier submitted by the user. This Network Access Identifier [RFC2486] contains information about the trust domain or trust realm the user belongs to. Based on a simple discovery mechanism a provider can establish a trust path to this home network. Once this is established, the provider can authenticate the user and check his credit with the home network. Accounting and rate information will be sent to the home network for mediation and processing.