Edit /etc/asterisk/extensions.conf
go to bottom add the following under [voipms-inbound]
exten => 2242179435,1,Answer
exten => 2242179435,n,NoOp(Inbound-Call)
exten => 2242179435,n,Dial(SIP/101,24)
exten => 2242179435,n,Voicemail(101@internal-vm)
.