A method of exchanging data packets between a first portable communication device and a second portable communication device over a bi-directional wireless communication channel, where at least one of the first and second portable communication devices comprises a hearing instrument; said method comprising steps of: - generating, by the first portable communication device, a first data packet belonging to a first packet category (200a, 200b) comprising audio data or to a second packet category without audio data (200c, 200d), and adding an acknowledgement indicator with a default setting to the first data packet, - transmitting the first data packet from the first portable communication device to the second portable communication device through the wireless communication channel, - monitoring, at the first portable communication device, the wireless communication channel for a second data packet transmitted by the second portable communication device subsequent to receipt of the first data packet, if the second data packet is absent: - unseting the acknowledgment indicator of the first data packet to reflect failed receipt of the second data packet and retransmitting the first data packet from the first to the second portable communication device for at the most N times if the first data packet belongs to the first packet category (200a, 200b), and - flushing or abandoning the first data packet if the first data packet belongs to the second packet category (200c, 200d); - if the first portable communication device receives the second data packet checking an error-detection code of the second data packet; if the error-detection code indicates invalid data of the second data packet ignoring the acknowledgment indicator of the second data packet and generating, at the first portable communication device, a third data packet with unset acknowledgment indicator to reflect the invalid data of the second data packet; if the error-detection code indicates valid data of the second data packet and an acknowledgement indicator of the second data packet is set: - setting the acknowledgement indicator of the third data packet to reflect successful receipt of the second data packet, and transmitting the third data packet to the second portable communication device through the wireless communication channel; N being a positive integer between 1 and 4. - generating, by the first portable communication device, a first data packet belonging to a first packet category (200a, 200b) comprising audio data or to a second packet category without audio data (200c, 200d), and adding an acknowledgement indicator with a default setting to the first data packet, - transmitting the first data packet from the first portable communication device to the second portable communication device through the wireless communication channel, - monitoring, at the first portable communication device, the wireless communication channel for a second data packet transmitted by the second portable communication device subsequent to receipt of the first data packet, if the second data packet is absent: - unseting the acknowledgment indicator of the first data packet to reflect failed receipt of the second data packet and retransmitting the first data packet from the first to the second portable communication device for at the most N times if the first data packet belongs to the first packet category (200a, 200b), and - flushing or abandoning the first data packet if the first data packet belongs to the second packet category (200c, 200d); - if the first portable communication device receives the second data packet checking an error-detection code of the second data packet; - unseting the acknowledgment indicator of the first data packet to reflect failed receipt of the second data packet and retransmitting the first data packet from the first to the second portable communication device for at the most N times if the first data packet belongs to the first packet category (200a, 200b), and - flushing or abandoning the first data packet if the first data packet belongs to the second packet category (200c, 200d); - if the first portable communication device receives the second data packet checking an error-detection code of the second data packet; if the error-detection code indicates invalid data of the second data packet ignoring the acknowledgment indicator of the second data packet and generating, at the first portable communication device, a third data packet with unset acknowledgment indicator to reflect the invalid data of the second data packet; if the error-detection code indicates valid data of the second data packet and an acknowledgement indicator of the second data packet is set: - setting the acknowledgement indicator of the third data packet to reflect successful receipt of the second data packet, and - setting the acknowledgement indicator of the third data packet to reflect successful receipt of the second data packet, and transmitting the third data packet to the second portable communication device through the wireless communication channel; N being a positive integer between 1 and 4.