don’t you ever sleep ?? 🙂
i’ll check if there is any history on such problem.
on your side, could you see exactly how are transmitted these “tones” ? are they sent over TCH or FACCH or SDCCH ?
you would need to find the message flow, and therefore get in touch with the company that builds the modem (??)
I suspect they are using “Supplementary Services” ?
>> Pan “Mr 3GPP”, what do you think ?
you could check the MC02xx associated with supp services.