USe of Transfer cmd to sips: contact

Hi, using ver 1.6.2.8 . I wish to simply use the Transfer comand to transfer to sips uri. So that in the contact
header fo the 302 message

the contact is like this sips:username@domain

I tried Transfer(sips:username@domain) but this results in contact header sip:sips:username@domain

Please can someone say how to do this, thanks