Active forwarding to local users

1. An external user A makes a call to an internal user B (SIP, ISDN or analog).
2. B makes an additional call to a local user C. These two users can call each other directly, and so the LANCOM VoIP Router only handles the signaling via SIP; the data transfer via RTP takes the shortest possible route.
3. The local user B then transfers the call (with consultation) to C.
4. The LANCOM VoIP Router manages the call transfer.

Active transfer to external SIP users

1. An external SIP user A makes a call to an internal user B (SIP, ISDN or analog).
2. B makes an additional call to an external user D.
3. If the two external SIP users A and D can be accessed over the same SIP line, the LANCOM VoIP Router delegates the management of the call transfer to the upstream provider.

Active transfer to external ISDN or analog users

In some cases upstream exchanges do not support the delegation of call-transfer functions to external ISDN or analog users, often due to the unclear situation about who carries the call charges. For this reason, call transfer between external subscribers is always handled by the LANCOM VoIP Router.

1. An external subscriber A (external SIP, ISDN or analog) calls an internal user B (SIP, ISDN or analog).
2. B makes a further call to an external subscriber D (ISDN or analog).
3. The local user B then transfers the call (with consultation) to A.
4. If the two external users A and D use different protocols (SIP, ISDN or analog) then the LANCOM VoIP Router handles the management and conversion of the data.
5. If both external users A and D use SIP the LANCOM VoIP Router cannot enable the call transfer.

Passive forwarding between local users

1. An internal user B (SIP, ISDN or analog) calls an external user A (at a SIP PBX line).
2. A makes an additional call to a local user C.
3. The external user A then transfers the call to C.
4. The LANCOM VoIP Router manages the call transfer. If the connected subscribers B and C are internal users, the LANCOM VoIP Router controls the SIP data for signaling only and enables RTP-based data transfer over the shortest possible route directly between the SIP users.

Passive transfer from local to external users

1. An external user A (at a SIP PBX line) makes a call to an internal user B (SIP, ISDN or analog).
2. A makes an additional call to an external user D (who is also a subscriber to the same SIP PBX line as A).
3. The external user A then transfers the call from B to D. To do this, the LANCOM VoIP Router has to open an external connection to D.