Hello, in OSB, the Networking license opens channels for interconnection with other pbx, for example, Asterisk via Native SIP, or against Siemens / Unify pbx. It allows nodes to be configured. Otherwise, the CUB-646 S2M-SIP-T1 trunk licenses are used to activate lines against PSTN. If a ITSP trunk has, for example, 30 channels, you must have 30 of these licenses. I hope this answer helps. Best regards!