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Problem: Hollow Sound

This is generally due to a high level of echo with a small amount of delay. For example, if an IP phone was connected over a LAN to a VoIP Gateway then the delay would be very small – echo that occurred on the trunk side of the Gateway may cause “hollowness” in the IP Phone.


Users may report that calls sound "hollow", "cavelike" or "tunnel-like".

Example audio file:


Initially try and locate the source of echo - often on the analog loop connected to a Gateway. The echo canceller in the Gateway should compensate for echo however may not operate correctly if mis-configured or if the loss plan is incorrect.

If the problem seems to be associated with a particular telephone handset then it may be due to internal feedback - consider using a different handset.

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