Sonus ( SONS) says it needs another 15 days to finish its annual report.

The Westford, Mass., maker of networking gear is still working to clean up its books after an internal audit uncovered accounting questions last month.

Shares fell 50% in the weeks immediately after the company said it would not be able to report its fourth-quarter and full-year results. The company has fired a few managers and hired blue-blood Boston law firm Hale & Dorr to assist in an internal probe with PricewaterhouseCoopers.

Sonus said the audit uncovered an issue of revenue timing related to some transactions. Sonus has said that equipment was shipped and received by the customers, and the company has either received payments or is receiving payments.

"Over the past two months, we have put a great deal of effort toward completing the review of our financials and establishing new practices and controls," said CEO Hassan Ahmed in a press statement.

Sonus says it expects to file a partial annual report with the Securities and Exchange Commission Monday, but that document will not contain the audited financial statements.

Gear peer Nortel ( NT) has also run into revenue timing issues, which were uncovered during an internal audit. Some observers say Nortel's accounting misadventures may have initiated an SEC probe. Nortel also said Monday that it has hired two interim accounting officials as it completes its internal audit.

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