54. In a switching system having an internal numbering plan, for use in a telecommunications network having a network numbering plan, the improvement comprising: data storage means for storing first contents defining the internal numbering plan that includes a first symbol sequence and defining the first symbol sequence as a feature access code for a feature of the switching system, and further for storing second contents defining the network numbering plan that includes a second symbol sequence different from the first symbol sequence, which second symbol sequence includes an extension number of the switching system, the second contents defining the second symbol sequence as a feature access code for said feature of the switching system; means responsive to receipt of the first symbol sequence, for parsing the received first symbol sequence by using the first contents of the data storage means to determine a meaning of the first symbol sequence within the internal numbering plan, and further responsive to receipt of the second symbol sequence, for parsing the received second symbol sequence by using the second contents of the data storage means to determine a meaning of the second symbol sequence within the network numbering plan; and means responsive to the determined meaning of either one of the received first symbol sequence and the received second symbol sequence, for invoking said feature in the switching system.
55. The improvement of claim 54 wherein the stored second information defines the second symbol sequence as an equivalent of the first symbol sequence; and the first symbol sequence is received from a user directly served by the switching system.