There is no "Calling-Station-Id" attribute in access-requests sent in response to radius challenge from pam_radius-1.3.17-2.el6.x86_64 (CentOS release 6.5)

Hi all, I'm using freeradius for custom 2-factor OTP authentication as below: RADIUS_CLIENT > Access-Request(User/Pass) > FreeRADIUS(check user pass and if ok -> generates state) > Access-Challenge > RADIUS_CLIENT> Access-Request(User/OTP/state) > FreeRADIUS In first Access-Request (before Access-Challenge) RADIUS_CLIENT is sending all required attributes well My problem is on the second Access-Request (after Access-Challenge). There is no "Calling-Station-Id" attribute on this state for some reason... I have checked this on the following radius client: pam_radius-1.3.17-2.el6.x86_64 (CentOS release 6.5) Anyone can suggest some work around for above? Maybe it is configuration issue I'm missing? Thanks a lot, Dmitry!