Embodiments of the present invention provide an open and interoperable single sign-on session in a heterogeneous communication network. The open and interoperable single sign-on system is configured by exchanging an entity identifier, an account mapping, an attribute mapping, a site attribute list, an action mapping and/or the like. The entity identifier, account mapping, attribute mapping, site attribute list, action mapping and the like for each partner entity is stored in a partner list accessable to the particular entity. Thereafter, the open and interoperable single sign-on session may be provided upon receipt of a SAML request or assertion containing an entity identifier. The entity identifier contained in the SAML request or assertion is looked-up in the partner list of the particular entity which received the SAML request or assertion. A record containing a matching entity identifier provides the applicable account mapping, attribute mapping, site attribute list, and/or action mapping. The one or more mappings are then utilized to process the SAML request or assertion.