g the call (assuming that Operator 1 bills A)? How many POIs between Operator 1 and Operator 2, and of what form? Who pays the cost for creating and maintaining the POIs? Figure 4.40 Many questions have to be solved between operators routing, numbering and other fundamental technical plans. The overall terms are usually regulated in a service level agreement (SLA). More on interconnect and SLA is found in Chapter 15, Section 15.5. Interconnect appears normally both as revenue and as a cost. Interconnect opens for roaming, where the subscriber can connect to visited networks, belonging to other actors. We can also speak of roaming among a number of technolo- gies provided that the terminals are equipped with such multiple technologies. Then we can also move between different access technologies belonging to different actors. Such possibilities of better use of access investments improve the ROCE value. An actual term is 'generalized roaming' with a need for appropriate business models for the actors involved. 4.6.3 ACCESS UNBUNDLING (REVENUE AND COST) For the local COPPER loop there are two possibilities for operators who do not own the access plant: To lease the copper line as it is. To share the use of the copper line. Example: the incumbent operates PSTN/ISDN. The new operator offers xDSL services. The copper pair ownership depends on the regulations. If the regulator has enforced 'copper unbundling' the incumbent operator no longer owns the copper access network. In this case the new operator can connect the subscriber in the same way as the incumbent. Another alternative for the regulator is to go for 'equal access'. In this case the incum- bent operator continues to own the copper, but the subscribers can choose their preferred operator and the incumbent must direct all calls to the pre-selected operator. (In Sweden, this has been the case since September 1999.) A third alternative is that the new operator builds an access network of its own. It is very costly to build a full copper network with pairs to all