We are using cisco SIP phones model 3951 & 7970/7961/7941 ip phones .
We have CCM version 5.x along with PSTN router 2851 on which PRI is terminated.
Problem which we are facing is that when we make a PSTN call from SIP phone 3951 to Mobile /Landline , Ringback tone which we get is "RINGING" even if the mobile phone at other end is switched OFF. Also , when call is made to Landline from SIP phone, the RBT which we get is RINGING even though , landline phone is busy.
But when the same calls are made from 79XX phones , situation is different. Call made to Mobile says the MOBILE is switched OFF which is correct since the MOBILE has been SWICTCHED OFF.
Can somebody help?