No Audio Public Facing Asterisk/ NATed Softphones

I currently have a setup connected public facing at a data center. My softphones are located on a NATed network. Registration between the softphone and Asterisk is successful. The issues are #1 one way audio #2 Partial audio.
I’m a little confused at to what modifications must be made to allow for successful communication.
I am aware of other explanations but the issue I find is that the majority of asterisk boxes are behind a NAT and not at a data center public facing.
Thanking the community in advance,

1.- Open the RTP ports in your firewall, view the rtp.conf to know what ports are using asterisk.
2.- Define an ExternIP or externhost in your sip.conf
3.- Define the localnet in your sip.conf.

Just to clarify the ExternIp should be the public ip of the server or of the remote NAT?

The public ip of the server.

In regards to the localnet since the server is public facing am i defining the nat address pattern of the remote extentions?

The localnet is the network that use your server locally i.e.:

localnet= <–this is the network in the office, where server is located.