ESP32 as slave Multiple SCO connection Limit problem

[ahmed_abdo]

I'm using the ESP32S module and btstack lateset version and esp-idf 4.4.3 using it to connect two phone devices.

When I have ACL connection to both of them the ESP32 and the Samsung A22 and iphone, I try to open SCO connection. And I can only open one. When trying to open the second one, the controller will respond with HCI ERROR: 0x0A (ERROR_CODE_SYNCHRONOUS_CONNECTION_LIMIT_TO_A_DEVICE_EXCEEDED)

I discovered that when the ESP32 is a master role it can open 2 SCOs successfully but when one or two of the phones are the master and the ESP32 is a slave only 1 SCO is opened and I get the above 0x0A error code.

Why this happens and how can I make the ESP32 when it is in a slave role to be able to open more than 1 SCOs.

Thanks in advance.