Post Dial Delay (PDD) & Ring Back Tone (RBT) Problems..!

I have a connection from Asterisk to MVTS II (Mera 2) switch… But we are having a lot of PDD and RBT issues… The PDD seems to be high, up to 30 seconds… We are getting dead air… In some instances but not always we are getting charged for the RBT… The calls originate from the MVTS II (Mera 2) switch and terminates to the Asterisk switch… Any ideas why is this happening or suggestions on how to fix it.? Thank you…

Given it is unlikely that people know that switch, which channel technologies are you using?

Generally you will need to obtain a detailed protocol trace from the channel technology driver to see hat is happening.