Is this happen on all analog extensions or only one extension,if this problem happens only on one extension,try to change the tel.set or restart the program unit for analog,RFPUI:LIM=location of analog extension,UNIT ELP6,restart the board RFBOI:LIM=X,BPOS=X-XX-XX;and then BLDBE:BPOS=X,ALLFM=YES.
Note:This solution is your system is MD or MX-ONE.