2. Present Addressing Protocol

Full Area Code Coverage
The simplest solution to this problem is to divide the NANP service area into the almost 800 area code combinations allowable, which appears to be the direction the telephone companies are taking. Even these may not suffice however. The Federal Communications Commission expects the available area codes to be exhausted at an accelerated rate(Green, 1996).
Overlay Approach
According to this approach several area codes are assigned to the same NPA (Rozansky, 1997). Consequently all calls within that NPA require ten digits to distinguish between the area codes. There is already public resentment against ten-character local calls however, which is increasing.
Unbound Groups
Another approach would be to lift the restrictions posed by bound groupings of three and four characters and simply add additional characters to telephone addresses as required. However this approach would require additional access codes to signal the number of characters to follow unless all addresses were revised simultaneously. Otherwise this approach would lead to an increase in misdialing as the number of characters required will change with the address: local versus long distance; four versus five line numbers, and would probably be rejected as incompatible with the NANP.
Fax Routing
To facilitate facsimile data transfer to several machines in different locations using the same facsimile address a suffix-group arrangement has been proposed by Human Communications (HumanComm) in conjunction with the Electronic Messaging Association (EMA) and standardized by the Telecommunications Industry Association (TIA) as IS-141. Each machine would have a sub-address in the form #<xx...x> with up to 20 characters following the NANP characters. The simplest arrangement would have three characters in the suffix group. For example:
Hence numerous facsimile data transfer terminals such as fax machines or computers located at the same installation or domain can be distinguished by their sub-addresses.
Ostensibly this arrangement could be extended to general telecommunication addressing:
def-ghij#01 Telephone
def-ghij#02 Facsimile
def-ghij#03 Cellular
def-ghij#04 Modem
However if the PSTN switch expects the suffix group then addresses without the group could not be connected. If telephones alone were exempt from using the suffix group then any hesitation before dialing the suffix group would result in a telephone connection or misconnection, unless some waiting period was included in the PSTN programming. Beyond this period the PSTN switch would understand that a telephone connection was being made, even if this was not the intent. This arrangement accordingly is not fully compatible with the present PSTN protocol. Worse, for general telecommunication addressing ten characters would be required for local calls and 14 for long distance using a minimal three-character suffix group. Practically, Fax Addressing is useful only for the very specific application for which it was developed rather than general addressing.
Integrated Messaging
According to Universal Message Services (UMS) a single workstation would control all communications for a subscriber: voice, facsimile, e-mail, whatever. Voice messages could be converted to text and text to e-mail, and facsimile to e-mail and e-mail to voice. Hence subscribers could specify the perceived format of their incoming messages. Responses would be converted into the same formal as was the incoming message. Hence UMS is a highly sophisticated messaging system that probably could not be fully implemented at present but promises to be extremely useful for the most demanding users of telecommunication services. Accordingly UMS would not be overly practical in ordinary commercial and residential service for the foreseeable future. Moreover UMS does not directly impact on overall addressing concerns.
Electronic Recognition
Telecommunications devices could be altered to transmit a recognition signal to indicate to the PSTN switch the device to be accessed. Hardware solutions however pose a myriad of problems, not the least being the public's perception that their telephones are obsolete or worse that a set box will be required, as for television cable access.