ernet traffic balancing). So, regarding the interconnection there are two main types of interconnection, and they are: (i) TDM interconnection (made initially for PSTN/ISDN interconnections, but also used for Internet traffic exchange later), and (ii) IP/Internet interconnection (over all-IP networks on both sides of the interconnection points, including the traffic originating/terminating from/to public Internet access and managed IP networks). 7.3.1 QoS Aspects for TDM Interconnection The telecom/ICT world is fully converging onto all-IP networks, but there are still many TDM transport networks in use that were initially designed for legacy telephony (e.g. synchronous digital hierarchy). Such TDM transport networks and their interconnec- tion points nowadays are also used for carrying IP traffic from the public Internet and managed IP networks. The main purpose of interconnection is to ensure end-to-end network service con- nectivity with desired QoS, and at the same time to enable customers of interconnected network operators to establish connections with one another. Table 7.3 defines several important QoS parameters (i.e. key performance indicators) for TDM-based points of interconnection (POIs) [7], and their possible thresholds val- ues. Such KPIs should be measurable and realistic to ensure effective interconnection regulation and mitigation of eventual disputes. Each interconnection between networks of different telecom operators is mainly a matter of mutual agreement between the interconnecting parties. However, the inter- connection capacity (e.g. number of channels/circuits, or bitrates), its expansion, and/or modification (including closing a certain POI) need to be mutually agreed. This can be driven by market forces in a given country (e.g. the POI capacity is expanded when the traffic increases over a given threshold at POI), but in less developed ICT markets (e.g. markets with dominant market position of the incumbent telecom operator) it is desir- able for national administrations to establish r