Communications between participants over a communications link are proxied by an intermediary, such as an Integrated Order Mechanism (IOM). Participants interact with each other through the IOM. The IOM may be transparent to the participants such that they are not aware that the IOM is involved in processing communications. For example, in the context of a transaction by a customer making a purchase from a merchant over the Internet, the IOM facilitates the processing of transactions by processing requests from both the customer and the merchant. Neither the customer nor the merchant may be aware that the transactions are being handled by the IOM. Transactions may be tracked using addresses in a communications network. Address identifiers may be used to reduce the size of the addresses.