Lucent Technologies Release 8.2 manual IP Softphone Problem Solving

Troubleshooting IP Solutions 2 H.323 Trunks

IP Softphone Problem Solving

Codecs used with Netmeeting

Telecommuter use of phone lines

NetMeeting drops unanswered calls

NetMeeting ignores out-of-band tones

Voice quality for the road-warrior application of DEFINITY IP softphone will vary depending on several factors. Poor voice quality can be caused by the use of the high-compression codecs (G.723 or G.729) in situations where the low-compression codec (G.711) should be used. This can happen unexpectedly when using NetMeeting

—when the G.711 is set as the preferred codec on the switch, NetMeeting may fail to use it. Since there is no way to monitor which codec is being used, the only way to determine that this is the problem is to disable all but the G.711 codecs. Then, if calls no longer work, it can be concluded that NetMeeting is failing to use the G.711. The solution to this problem is to reinstall NetMeeting.

The telecommuter application of the IP Softphone requires the use of two phone lines: one for the IP connection to DEFINITY, which is used for softphone registration and call signaling, and the other for a PSTN connection, which DEFINITY uses as a callback number to establish the voice path. How you allocate your phone lines to these two functions may make a difference.

For example, assume that you have telephone services provided by the local phone company, such as voice mail, associated with one of your lines and not the other. In this case, you should use the line with the services to make the initial IP connection to register the softphone and use the line without the services as the POTS callback for the voice path. Otherwise, there could be undesirable interactions between the softphone and the local services. For example, if your telecommuter application is registered and you were using your POTS callback line for a personal call when a business associate dialed your work extension, the business associate would hear your home voice mail message.

For calls made to a NetMeeting softphone, if the call is not answered or if coverage is not administered, after about 5 rings NetMeeting drops the call and the station stops ringing but the caller continues to hear ringback. To avoid this situation, make sure that coverage is administered for the NetMeeting softphone.

NetMeeting ignores any H.323 digits received out-of-band, so it never hears DTMF from DEFINITY, which always strips DTMF from the audio path and plays it out-of-band with H.323.

For example, if you are on a call on a NetMeeting softphone and the calling party presses a number or character on their keypad, you will not hear the tone.

		Administration for Network Connectivity
52	CID: 77730	555-233-504 — Issue 1 — April 2000