MT#7673 update voicemail number in webinterface

(cherry picked from commit d57aa0e7ff7e86dba80c4e0dadce683a455ece3c)
MT#8309 change boolean handling in api preferences

(cherry picked from commit ee9ad451bb299efe9cd579c58e6f2382549d8111)
MT#7673 update voicemail number in api

(cherry picked from commit 36e44a643950cc1540a6c0232e72c210d17fe6b5)