Asterisk 1.8 Exchange 2010 "Not accepting call completion

I have been using 1.6 for years with the

SIPAddHeader(Diversion:tel:${MACRO_EXTEN:3}>;reason=noanswer;screen=no;privacy=off) command.

Upon upgrading to 1.8 I get a "Huh? Not an RDNIS SIP header" error. I did some research and discovered that 1.8 no longer uses the Diversion command and is now favoring the REDIRECTING function to write a Diversion Header. After changing my test script to

exten => 2132759,1,Answer()
exten => 2132759,n,Dial(SIP/3801,3)
exten => 2132759,n,Set(REDIRECTING(from-num,i)=3801)
exten => 2132759,n,Set(REDIRECTING(from-num-pres,i)=allowed)
exten => 2132759,n,Set(REDIRECTING(reason,i)=cfnr)
exten => 2132759,n,Dial(SIP/6001@${vm})

the “Huh? Not an RDNIS SIP header” error is gone but now I get
"Not accepting call completion offers from call-forward recipient SIP/prodcexchcas03" back from Exchange.

After looking at several traces from 1.6 and 1.8, I find the following differences in the INVITE to Exchange.

1.6
The diversion looks like this
Diversion: tel:3815;reason=noanswer;screen=no;privacy=off

1.8
Diversion: sip:3801@64.6.215.68;reason=no-answer\r\n

1.6 is diverting using tel: and 1.8 is using a .

My questions are, does this look right? Is there a way to use tel: instead of a ? Is this even my problem or is something else going on? Am I using the REDIRECTING function correctly?

Here is more detail in the 1.8 trace:

Session Initiation Protocol
Status-Line: SIP/2.0 302 Moved Temporarily
Message Header
FROM: "5028153815"sip:5028153815@prodcexchcas03.prod.appriss.comm;tag=as36f7db2a
SIP Display info: "5028153815"
SIP from address: sip:5028153815@prodcexchcas03.prod.appriss.comm
SIP from address User Part: 5028153815
SIP from address Host Part: prodcexchcas03.prod.appriss.comm
SIP tag: as36f7db2a
TO: sip:6001@prodcexchcas03.prod.appriss.com:5060;epid=EE1E0DC808;tag=6af9f2c747
SIP to address: sip:6001@prodcexchcas03.prod.appriss.com:5060
SIP to address User Part: 6001
SIP to address Host Part: prodcexchcas03.prod.appriss.com
SIP to address Host Port: 5060
SIP tag: 6af9f2c747
CSEQ: 102 INVITE
Sequence Number: 102
Method: INVITE
CALL-ID: 001c55612105862167c2628a7486cc73@prodce … priss.comm
VIA: SIP/2.0/TCP 64.6.215.68:5060;branch=z9hG4bK4a47c7fb
Transport: TCP
Sent-by Address: 64.6.215.68
Sent-by port: 5060
Branch: z9hG4bK4a47c7fb
CONTACT: sip:6001@prodcexchcas03.prod.appriss.com:5067;transport=Tcp
Contact-URI: sip:6001@prodcexchcas03.prod.appriss.com:5067;transport=Tcp
Contactt-URI User Part: 6001
Contact-URI Host Part: prodcexchcas03.prod.appriss.com
Contact-URI Host Port: 5067
Contact parameter: transport=Tcp>
CONTENT-LENGTH: 0
SERVER: RTCC/3.5.0.0
Diversion: sip:3801@64.6.215.68;reason=no-answer
[Expert Info (Note/Undecoded): Unrecognised SIP header (Diversion)]
[Message: Unrecognised SIP header (Diversion)]
[Severity level: Note]
[Group: Undecoded]
Session Initiation Protocol (SIP as raw text)
SIP/2.0 302 Moved Temporarily\r\n
FROM: "5028153815"sip:5028153815@prodcexchcas03.prod.appriss.comm;tag=as36f7db2a\r\n
TO: sip:6001@prodcexchcas03.prod.appriss.com:5060;epid=EE1E0DC808;tag=6af9f2c747\r\n
CSEQ: 102 INVITE\r\n
CALL-ID: 001c55612105862167c2628a7486cc73@prodce … priss.comm\r\n
VIA: SIP/2.0/TCP 64.6.215.68:5060;branch=z9hG4bK4a47c7fb\r\n
CONTACT: sip:6001@prodcexchcas03.prod.appriss.com:5067;transport=Tcp\r\n
CONTENT-LENGTH: 0\r\n
SERVER: RTCC/3.5.0.0\r\n
Diversion: sip:3801@64.6.215.68;reason=no-answer\r\n
\r\n

Thanks in advanced for the help.

Kevin