ratanraj One-way audio is normally related to firewall/NAT issues. You need to check if your router has UPNP enabled and allows SIP or VoIP traffic.
For poor quality of calls since you're on a hosted system check the following:
- Softphone codec
- Agent workstation
- Bandwidth consumption
use bandwidth efficient codecs like g729. You might also need to check the agents workstations to see if they're not overloaded. Meaning they're just running the necessary applications for dialing (Firefox, softphone, noted or etc). Softphones eat CPU resources. If the workstation is overloaded then call quality can suffer.
Lastly, check your bandwidth consumption. You might be eating all your bandwidth connection. Make sure your internet connectivity is just being used for dialing purposes. Browsing social media sites like Facebook, Google+ and Youtube and others will eat up all your bandwidth.