Asterisk Features Call Tranfer DTMF is not working intermittently on Zoiper and MicroSIP

While on call the agent press *1 for atxfer, intermittently it works, some time on the same call when continuously press multiple times. please help me to find a solution for this.

[featuremap]
blindxfer => #1                
disconnect => *0               
;automon => *1                  
atxfer => *1                   
;parkcall => #72                
;automixmon => *3               

sip.conf

dtmfmode = rfc2833

using realtime mysql chansip

Hi david55 and jcolp, please help on this issue

Please provide RTP debugging and the DTMF log.

If I have anything of value to add on threads then I respond.

While im testing, its working now and not getting failed, i will update once its failed again