asterisk users - May 2013 - Temporarily features (transfer) off during Read

Hello all.

Dialing with tT options and function Read (to prompt number) has a 
trouble for me.
Can I temporarily features off during Read?

features.conf:
[featuremap]
blindxfer => ##                 ; Blind transfer  (default is #)
atxfer => **                    ; Attended transfer

I try:
exten => s,n,Set(LOCAL(tmp_atxfer)=${FEATUREMAP(atxfer)})
exten => s,n,Set(LOCAL(tmp_blindxfer)=${FEATUREMAP(blindxfer)})
exten => s,n,Set(FEATUREMAP(atxfer)=)
exten => s,n,Set(FEATUREMAP(blindxfer)=)
exten => s,n,Read(tmp_ext,${ARG1},${ARG2},${ARG3},${ARG4},${ARG5})
exten => s,n,Set(FEATUREMAP(atxfer)=${tmp_atxfer})
exten => s,n,Set(FEATUREMAP(blindxfer)=${tmp_blindxfer})

No success. FeatureMap is usefull only BEFORE Dial. It is no matter 
during Dial :(

Remark: It's difficult to remove option (tT) in Dial.

Got any ideas?
Thanks.

Dmitriy.