FS-3078 see wrapper function that should do the same thing this is called at the time when the sdp is created so if it still doesn't work it would suggest that you have this variable set passing in from the other leg in which case you need to set it explicitly because the mode of the inbound leg prevails over the profile default

src/mod/endpoints/mod_sofia/sofia_glue.c

@@ -826,6 +826,8 @@ void sofia_glue_attach_private(switch_core_session_t *session, sofia_profile_t *
 		tech_pvt->recv_te = tech_pvt->te = profile->te;
 	}
 
+	sofia_glue_check_dtmf_type(tech_pvt);
+
 	if (!sofia_test_pflag(tech_pvt->profile, PFLAG_SUPPRESS_CNG)) {
 		if (tech_pvt->bcng_pt) {
 			tech_pvt->cng_pt = tech_pvt->bcng_pt;