Sotir Rangelov 

I'm no expert on this, but I think your only really sensible option would be to obtain an export to DOCX from your customer and translate that.  I know a *.pages file is essentially a zip, so you can unzip it gate some interesting benefits, but I don't think a file you can translate is one of them.  I believe older versions used to contain a PDF for previewing, and maybe saving with Word compatibility might have added a DOC (I'm not 100% on this), but neither are really helpful since translating them can't be repacked to update the Pages file.

I think the best process is probably this:

• Convert the Pages document to a DOCX file through Pages itself, if you have access to a Mac or iPad with Pages installed. This ensures the file is properly formatted for Word.
• Translate the DOCX file using your preferred translation method or software.
• Open the translated DOCX file in Pages. Pages is capable of opening DOCX files directly. You can then save the document as a new Pages file.

Not perfect, but probably the best solution.  I guess anyone handling customers who use this format a lot should probably invest in a MAC and charge for the necessary DTP.

Just an aside, but I often wonder about MAC.  Whilst only a few CAT tools will run on it, I'm not aware of any that can handle their file formats.  I always find that surprising as you'd think, if there really a serious demand for this, someone would have done it by now!!

Thank you for your reply and thoughts. 
I succedded to save the files to a lower version (09) and exported the XML file from the archive. I opened it in Trados without any issues. So I will continue with the translation of this file without conversion.

P.S. This is strange indeed - so many translation and localization needs in USA and no CAT tool is able to process .pages?! Maybe the clients do not provide the text in .pages but in DOCX format?!

Best regards,

Sotir