8. Implementation

PSTN Concerns
A century after the telephone was introduced most residential subscribers still have plain old telephone service. They would not be affected whatsoever by the introduction of the MTAS in any area because their primary telephone address is not altered by the MTAS. Accordingly CLASS such as Caller ID, Call Forwarding, Call Block and so forth, are not affected by MTAS. In this respect MTAS differs most greatly from the addressing options being considered for the Long Term Numbering Plan. The compatibility of MTAS with the Long Term Numbering Plan is discussed in detail in the NANP Expansion Report issued by INC, which has been emended for this purpose.
Special Services
MTAS is directly compatible with Extended Emergency Service <911>. As for Fax Routing, a specific MTAS extended-service marker, for example <#*#>, might indicate that a suffix group would follow the PSTN address in accordance with the Fax Routing protocol.
This concept can be carried beyond Fax routing however, as is illustrated below:



The final three tones are audible access signals transmitted after the connection is made to distinguish between related devices. Using <*##> for example, numerous devices can be accessed.

Each different utility would use their own audible code to access their own metering device.
Hence MTAS can handle utilities not yet devised. Of course such addresses would be automatically dialed.
Of course this same arrangement can be used for bank branches for example, with special services such as automated teller machines and terminals accommodated by sub-addresses. Simultaneous access to multiple terminals could be accommodated by multiplexing. Similarly with modern supermarkets, which require just about the same special services, including automated teller machine access.


It is evident from these example that any of these special services can be piggybacked on MTAS, whether Universal Messaging Service, Fax Routing, or any of the acceptable options of the LTNP. MTAS compatibility is evident because even after MTAS is implemented in any NPAs it would be invisible until accessed. The presence of MTAS is imperceivable to all users except those subscribing to its services.
PBX Concerns
Only the most recently installed Private Branch Exchange (PBX) systems have routing and control functions equivalent to PSTN electronic switching. Although some PBXs recognize <*> and <#> tones for special services, in general they are simply plain old telephone exchanges. PBXs would not be compatible with LTNP because the PBX switches will not be able to recognize a priori whether the address dialed had one greater or one fewer digit. Consequently LTNP will require all PBXs to be upgraded before LTNP implementation. This will not solve the compatibility problem however during the transition period. In contrast, because MTAS is fully compatible with the present addressing protocol, PBX systems need only be upgraded at the time MTAS services are subscribed.
WATS Concerns
Incoming Wide Area Telecommunication Service (WATS) is a reverse-charge billing system not consistent with the NANP scheme. Although the WATS code <abc> resembles an area code it has no assigned NPA. Nevertheless, by reprogramming SS7 a billing system was implemented wherein the call receiver would automatically be billed for the telephone charge rather than the call originator. In practice an NANP-wide WATS code <abc> prefixes the telephone address assigned to the subscriber.
WATS has become so popular with commercial firms dealing directly with the public that the originally assigned WATS code <800> has been essentially filled and two new codes have been assigned: <877> and <888>, further consuming the available NANP area codes.
MTAS would supersede WATS, although preserving the concept. Instead of a centrally adminstered WATS database a specific MTAS extended-service marker, for example <###>, would indicate that there is a toll-free sub-address of a firm's primary telephone address. For toll-free fax transmission another extended-service marker, perhaps <##*> could be employed. Unlike WATS codes, the MTAS area code is fully consistent with the NANP.
Sub-Address Resolution Concerns
MTAS permits a very practical means of transferring to the user the responsibility of resolving the sub-addresses, thereby relieving the LEC of this responsibility. The required Address Resolution Device (ARD) would be located at the user's site, with the purchase and maintenance of the ARD the user's responsibility. If a residential user has two or more sub-addresses the user could be enticed to acquire an ARD by the LEC offering a rate discount.


The ARD, being the responsibility of the residential subscriber, would be located within any residence beyond the residential Telephone Network Interface device. If the ARD were located at the entrance point of the telephone line, it would be convenient to utility meters, alarm systems, and other special service devices.
MTAS would be particularly advantageous to LECs for commercial subscribers as far as resolving sub-addresses are concerned.


All of the addresses and sub-addresses assigned to any one commercial domain would be bundled at the COX and routed to that domain. The PBX at that domain would simply route each bundled sub-address to its assigned user site, relying on the site ARD to resolve the sub-addesses.