The invention concerns a computer-implemented method for executing call control for a client (CI1) on a telephone terminal (30) representing a user (U1), comprising the following steps: a logic unit (L1) of a port handler (20) transmits a first call (C1) through a first trunk receiving unit (ET1) representing a first trunk (T1) to a first sending unit (SU1) assigned to the user (U1), by processing a first identification (ID1) received through the first trunk receiving unit (ET1), the logic unit (L1) assigns the first trunk receiving unit (ET1) and the first call (C1) to the user (U1), using an appropriately structured database DB1 and allocation table (Z1), the logic unit (L1) transmits at least a second call (C2) through a second trunk receiving unit (ET2) representing at least one second trunk (T2) also to the sending unit (SU1) assigned to the user (U1), by processing a second identification (ID2) received through the second trunk receiving unit (ET2), the logic unit (L1) assigns the second trunk receiving unit (ET2) and the at least one second call (C2) also to the user (U1), using the database (DB1) and allocation table (Z1), and the switching-capable sending unit (SU1) assigned to the user (U1) and a switching-capable receiving unit (EU1) assigned to the user (U1) use the client (CI1) to effect call control for the first call (C1) and the at least one second call (C2) to the telephone terminal (30) representing the user (U1). The invention further concerns an appropriately configured port handler and a machine-readable data carrier (90) with a computer program product stored on it.