Receiving call does not hear

I made a call to a government service and after entering a DTMF to get through the menu my encrypted connection maintained the connection to the dialed number and I could hear the person speaking but they could not hear me. Can anyone suggest how a encrypted VOIP connection connects allows DTMF through but the person cannot hear. What would cause such an issue ?

What platform are you doing your call on (PC, softphone?…)?

Both. I have 2 softphones and a ATA

Answering your specific question (how DTMF can pass and audio fail): DTMF may or may not be transmitted through the RTP voice channel depending upon settings on voip.ms control panel. Look at DTMF Mode on the sub-account settings and check the help information.

The INFO setting would send DTMF via SIP.