We have included a Dialing Plan Engine (DPE) software component in the SSL in order for other components in the SSL to access DPE services. The DPE allows the SSL object to 'learn' the dialing plan rules for a given network. Input strings are submitted from a SSO instance to the DPE. The DPE analyzes the strings, performs necessary modifications and operations and returns a result comprising commands or subsequent instructions to the SSO instance. The DPE analyzes the input string to identify which call formats, code prefix, and/or Supplementary services apply to the call. Examples of call format include local call format, domestic long distance call format, and service call. The DPE also recognizes user-dialed Carrier Identification Codes which enables the calls to be implemented by the identified carrier; it recognizes user-dialed errors such as, partial digits, and missing code prefix and it responds appropriately to these errors.