[asterisk-ss7] Send call directly to gsm voicemail

[Vallimamod ABDULLAH]

Hello List,

I have a user asking me for a way to call a gsm phone in ss7 and reach directly the voicemail without making the phone ring even it is connected.
Does anybody know of a way to achieve this (tell the callee carrier to connect the call directly to the voicemail)? Perhaps with a custom isup IE?

Thank you!

Best Regards,
Vallimamod.