If the trunks are ITSP trunks, 'MOH with ringing tone' does not apply due to system design. This applies to OpenScape Business S as on the X variants.
In case of blind transfer, ITSP callers will hear all the time MOH until connection with the new station (no ringback tone).
Parameter: MOH with ringing tone
If this option is selected, in the case of an unmasked transfer, the caller will hear Music on Hold while the transfer takes place. As soon as the call is transferred through by the transferring party and the external connection is ringing at the transferred destination, the caller will hear a ring tone.
The MOH with ringing tone option should always be set in a network system in order to provide the customer with a uniform environment.
If the caller is reaching the system through Internet Telephony Service Provider(ITSP), this option will not apply and the caller will hear Music On Hold during transfer.