Be sure that your equipment is connected before you begin to use Microsoft Lync 2010 Attendant communications software. Audio quality for Lync 2010 Attendant depends on the condition and quality of the network and devices you use.
If there’s a problem, typically a notification is displayed in the conversation or Lync 2010 Attendant window (above the Contacts icon). Generally, you can click the notification to get more details or suggested solutions.
Be sure that your speakers are turned on and that you have not muted sound in Windows.
If you’re not getting sound through your speakerphone, be sure that the handset is on the cradle. Check that the speaker volume is high enough to be audible. Use the volume keys on the phone keypad to adjust it. Also, verify that the phone is selected as the speaker and microphone device:
Lync 2010 Attendant handles a wide range of devices and still maintains high quality audio and video. However, certain devices may cause echo in the call. To reduce echo for a problematic device, Lync 2010 Attendant triggers a voice switching mode, which limits the ability for talkers to speak at the same time.
Common causes for poor device quality include the following:
To improve device quality, try the following:
Setup should detect your phone and any other compatible communications devices you are using, such as a headset, webcam, microphone, and speakers. You can also add devices after you install Lync 2010 Attendant.
To ensure that your devices are set up correctly, do the following.

Note To switch devices while in a conversation, click the audio device icon at the top of the main Attendant window, and then click the appropriate device in the menu. To switch the default device that Lync 2010 Attendant uses when you answer a call, click the audio device icon at the top of the main Attendant window, and then click Set Up Audio.
Lync 2010 Attendant supports IM text and presence only in a remote desktop session. Telephony and audio/video conferencing is not supported. You can redirect or decline incoming calls but cannot configure an audio device to make outgoing calls or accept incoming calls.
TTY mode is used for text communication via a telephone line. A TTY device must be connected to interpret the modified audio, otherwise users may experience poor audio quality in the call. Also, if you use TTY mode in a conference call, audio quality issues may occur.
TTY mode is turned off by default. You can turn on TTY mode from the Phones tab in the Options dialog box. You will then need to sign out of Lync 2010 Attendant and back in to use the feature.