Need Dialed Number in SIP "To:" header field

I am trying to connect FreePBX to IVM voicemail by NCH.
The voicemail system registers with FreePBX as extention 199.
When connecting to a mailbox the SIP “To:” header field to needs to contain the mailbox extention.
When dialing mailbox 101, The SIP INVITE should contain [email protected] and the TO: field would be [email protected]

Here is a log of their IP PBX connecting to voicemail: (Replaced <> with [] to show field in post)

20:23:12 UDP Packet Received from 127.0.0.1:5060 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
INVITE sip:[email protected]:5070;target=101%40voicemailserver;cause=486 SIP/2.0
Via: SIP/2.0/UDP 10.11.11.205:5060;rport;branch=z9hG4bK253292
To: [sip:[email protected]]
From: "101"sip:[email protected];tag=3277
Call-ID: [email protected]
CSeq: 14 INVITE

I have tried
exten => _XXXX,1,Set(CALLERID(dnid)=101)

and

exten => _XXXX,1,Goto(my-context,101,1)
exten => 101,1,Dial(SIP/199)

and

exten => 101,1,Dial(SIP/199/101)

Mike