I came across few codes for Nokia cell phones……out of which, I cannot understand the purpose of two of them. Will anybody explain it?
*3370# to activate Enhanced Full Rate (*efr0#)
#3370# to deactivate Enhanced Full Rate (#efr0#)
*4720# to activate Half Rate (*hra0#) ONLY IN SOFTWARE VERSION V4.33 OR EARLIER
#4720# to deactivate Half Rate (#hra0#)
After pressing these codes the phone will shut down and start up again with the service activated/deactivated.
Using the code makes no difference, as the phone already automatically negotiates the best codec that the network supports. Trying to enable it, if the network doesn't support it for the moment, makes no difference. If the network supports it, it is already used without any action required by the phone user.