I've had again a number of questions regarding Google SEO and why Google isn't showing certain .tel domains high enough (or, why they dropped dramatically in rankings). Google hasn't changed its indexing or ranking behavior on .tel domains, and similarly, .tel domains (as any others) must abide by the standard Google rules.
In general, domains get dropped in rankings for one of a few reasons:
1- duplicate content
2- duplicate content
3- duplicate content
As Google says: "Don't create multiple pages, subdomains, or domains with substantially duplicate content."
What is duplicate content? Google has a full page explaining it at http://www.google.com/support/webmasters/bin/answer.py?answer=66359.
Google despises duplicate content and states: "in some cases, content is deliberately duplicated across domains in an attempt to manipulate search engine rankings or win more traffic. Deceptive practices like this can result in a poor user experience, when a visitor sees substantially the same content repeated within a set of search results."
You MUST either get rid of the duplicate .tels or find a reason to put different content in these different domains. Can you find something unique so the information is different in each .tel? If not, then Google will think you're spamming its index with much of the same.
If you choose to write different content for each of your .tel, I suggest you still choose one "main" .tel that you're going to put most of your link power on. Take a well-indexed domain of yours on Google, and create a link from there to your main .tel, which will help it go up in the rankings.
But again, long story short, never ever duplicate content across sites (whether .com or .tel) or Google will dramatically penalize you.