diff --git a/libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn_stack_hndl.c b/libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn_stack_hndl.c
index 41833c54d3..5b0e1b5810 100644
--- a/libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn_stack_hndl.c
+++ b/libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn_stack_hndl.c
@@ -968,6 +968,18 @@ void sngisdn_process_sta_cfm (sngisdn_event_data_t *sngisdn_event)
 						//ftdm_set_state(ftdmchan, FTDM_CHANNEL_STATE_RESTART);
 						break;
 				}
+				break;
+			case 25: /* Overlap receiving */
+				switch (ftdmchan->state) {
+					case FTDM_CHANNEL_STATE_COLLECT:
+						/* do nothing */
+						break;
+					default:
+						ftdm_log_chan(ftdmchan, FTDM_LOG_CRIT, "Don't know how to handle incompatible state. remote call state:%d our state:%s\n", call_state, ftdm_channel_state2str(ftdmchan->state));
+						//ftdm_set_state(ftdmchan, FTDM_CHANNEL_STATE_RESTART);
+						break;
+				}
+				break;
 			default:
 				ftdm_log_chan(ftdmchan, FTDM_LOG_CRIT, "Don't know how to handle incompatible state. remote call state:%d our state:%s\n", call_state, ftdm_channel_state2str(ftdmchan->state));
 						//ftdm_set_state(ftdmchan, FTDM_CHANNEL_STATE_RESTART);