Compressed Real-Time Protocol (cRTP) needs to operate on both ends of each WAN link. If it is not configured or operating properly at one end, one-way audio may result. The user at the end that does not have cRTP operating correctly will not hear the user at the other end.
To resolve this issue, perform these steps:
- Check that the ip rtp header-compression or frame-relay ip rtp header-compression command is configured correctly on both sides.
- Check the Cisco Bug Toolkit for cRTP bugs in the Cisco IOS Software version you are using.
For more information about resolving one-way voice problems, refer to Troubleshooting One-Way Voice Issues.