Method for controlling a phone call initiated by a first terminal connected to a communications network via an operator network, the method including the implementation by a server (AS, PCRF) of the operator network of steps of: (a) receiving a request to set up a phone call between the first terminal and a second terminal, said request including an identifier of the first terminal, an identifier of the second terminal and at least one initial descriptive parameter of said phone call; (b) determining whether a degraded call mode must be activated by means of an interrogation of an identifier database according to the identifier of the first terminal and the identifier of the second terminal, the degraded mode of communication being activated when said identifier database indicates that the number of calls of the first terminal to the second terminal is greater than a threshold, or that the duration of the communications emitted by the first terminal destined for the second terminal is greater than a threshold; (c) if the degraded call mode is activated, ∘ modifying the initial descriptive parameter, ∘ transmitting a message to a management server (P-CSCF) of the operator network, said message including the modified descriptive parameter and being intended to set up the phone call via the communication network or to modify the phone call in progress between the first terminal and the second terminal, the modified descriptive parameter representing a degraded call quality compared with the initial descriptive parameter. (a) receiving a request to set up a phone call between the first terminal and a second terminal, said request including an identifier of the first terminal, an identifier of the second terminal and at least one initial descriptive parameter of said phone call; (b) determining whether a degraded call mode must be activated by means of an interrogation of an identifier database according to the identifier of the first terminal and the identifier of the second terminal, the degraded mode of communication being activated when said identifier database indicates that the number of calls of the first terminal to the second terminal is greater than a threshold, or that the duration of the communications emitted by the first terminal destined for the second terminal is greater than a threshold; (c) if the degraded call mode is activated, ∘ modifying the initial descriptive parameter, ∘ transmitting a message to a management server (P-CSCF) of the operator network, said message including the modified descriptive parameter and being intended to set up the phone call via the communication network or to modify the phone call in progress between the first terminal and the second terminal, the modified descriptive parameter representing a degraded call quality compared with the initial descriptive parameter. ∘ modifying the initial descriptive parameter, ∘ transmitting a message to a management server (P-CSCF) of the operator network, said message including the modified descriptive parameter and being intended to set up the phone call via the communication network or to modify the phone call in progress between the first terminal and the second terminal, the modified descriptive parameter representing a degraded call quality compared with the initial descriptive parameter.