Returning to the original question i think that in Ericsson there are not forbidden HSNs.
But due to the procedure used by the mobile stations for measurement reporting, the use of cyclic hopping with a multiple of 13 frequencies should be avoided when DTX is used. (For measurement reporting when using DTX, a subset of TDMA frames, SACCH, are used for the measurements which is sent every 13:th TDMA frame)