Networks

Access Networks

For most credit card applications, the cost of the access network is the single biggest factor in overall costs, often accounting for over half of the total. For that reason, there are many different solutions, depending on the provider, the application, and geographical constraints.

The simplest form of access network uses 800 service, in one of its many forms. Terminals at merchant locations across the country dial an 800 number that is terminated on a large hunt group of modems, con- nected directly to the acquirer's front-end processor (FEP). The FEP is typically a fault-tolerant machine, since an outage here will take out the entire service. A large acquirer will typically have two or more centers for terminating the 800 service. This allows better economy, due to the nature of 800 service tariffs, and allows for di- saster recovery in case of a failure of one data center. An advantage of 800 service is that it is quite easy to cover the entire country with it. It also provides the most effective utilization of your FEP resources. (A little queuing theory will show you why.) However, 800 service is quite expensive. It always requires 10 (or 11) digits di- aled, and in areas with pulse dialing it can take almost three seconds just to dial 1-800. The delay between dialing and connection is longer for 800 calls than many other calls, because of the way the calls get routed. All of this adds to the perceived response time at the mer- chant location, even though the acquirer has no control over it.

Large acquirers prefer to offer some form of local access service. In this service, terminals at the merchants dial a local telephone number to gain access to the acquirer. Typically, the local number actually connects to a packet network, which then connects to the acquirer. If the packet network is a public network, the terminal must go through a login sequence to get connected across the packet network. Typically, local calls are much less expensive than 800 service calls, and local calls typically connect faster than 800 calls. The cost of those calls are absorbed by the merchants directly. In those few remaining areas where local calls are still free from a business line, this works out well for the merchant. Otherwise, the merchant can end up spending a lot of money on phone calls. Usually, the acquirer has to offer lower prices to accepters who use local calls, to help offset this. Even so, these networks are generally much less expensive for the acquirers. Such networks are difficult to maintain, due to the distributed nature of the access network. Since most packet networks are much more likely to experience failures than the phone network is, the merchant's POS terminal is usually programmed to dial an 800 number for fallback if the local number doesn't work. Also, it is generally not cost effective to cover every free calling area in the entire country with access equipment, so some 800 service is required anyway. There is also an administrative headache associated with keeping track of the different phone numbers that each merchant across the country needs to dial. When you have tens of thousands of terminals to support, this can be formidable.

Acquirers are beginning to experiment with Feature Group B (FGB) ac- cess. FGB access was the method of access used to get to alternative long-distance carriers before "equal access" was available. The tariffs are still on the books, and they are favorable for this appli- cation. FGB access provides a single number, nationwide, for all mer- chants to dial in order to gain access to the acquirer. The call has simpler (hence, presumably, faster) routing than 800 service, and the call is charged to the acquirer, not the accepter. FGB access does have to terminate on equipment that is physically located in the Local Access Toll Area (LATA) where the call originated, so there is the problem of having distributed equipment, as above. This also implies that it is not cost-effective to deploy FGB access everywhere, as well. There are also some technical oddities of FGB, due to its original in- tent, that have made it difficult to implement so far.

The other big switched access capability that is likely to have an im- pact in the future is ISDN. So far, this has been inhibited by limited availability and lack of adequate equipment on the merchant end, but it could be very beneficial when these problems are solved.

Private-line networks are pretty straightforward applications of point-to-point and multipoint private lines. Since private lines are quite expensive, engineering of the networks is challenging. Usually, sophisticated software is used to determine the optimum placement of concentrators in order to minimize costs. Since tariffs, real estate prices, and business needs change frequently, maintaining a stable, cost-effective network is hard work. A typical asynchronous private line network will have multiplexers at remote sites, with backbone links to companion multiplexers at a central site. Synchronous private line networks may use multiplexers, or remote controllers, or remote FEPs, depending on the application and the availability of real estate.