Thank you for your enigmatic answers muhammad and to pix also.
I would like to clarify this concern,since,sometimes, “no answer” issue resulted from the user behaviour, who doesn’t answer the call when his/her cellphone rings,but perhaps it could be the result as well when the called subscriber’s cellphone received a loss of signal from the cellsite at the time when the calling subscriber calls the said subscriber,then the calling party received a “no answer” display from his/her cellphone at the same time no RBT heard.
Another phenomenon on the “no answer” issue incurred before “error in connection” displayed on the cellphone of a calling party after the said party initiates a call to the called party.
I am referring this on the GSM platform not on the PSTN side…
I hope you can share me as well on how to improve and minimize the said issue.
Your contribution to this is highly appreciated.