1. A method of communication among telephony services using an event context cache comprising: in a messaging telephony service, receiving a telephony event from a node in the public switched telephony network specifying a called directory number, a calling directory number, and service context data; storing said service context data as an entry within said event context cache, wherein said event context cache is accessible by at least one other telephony service; and associating said entry with a key for said event context cache, said key specified by said called directory number and said calling directory number.