No GSM sounds working


I am having some problems with the system sounds of asterisk.
Until yesterday i the GSM sounds from various sources (music on hold, ivr menu,voice mail) worked perfectly, but since today , they are not working, even though i can see from the server they are being played.Also if i establish a call i can hear them but, if i put the call on hold from either terminal, the call just mutes.
Can anyone help?

What version of Asterisk? What channel driver is in use? If using SIP is NAT involved and what is the network layout? What is the console output? And again if using SIP turn on the appropriate logging (sip set debug on for chan_sip or pjsip set logger on for chan_pjsip)