Keep getting eror message: "Iphone ineligible for requested build" when trying to restore Iphone 3GS in recovery mode.All software up to date.

Hi there,

A bit of background: phone was thought stolen and declared to Police as such. Found it later and cancelled theft declaration. In meantime provider had blacklisted IMEI number. After IMEI number was rehabilitated, was instructed by provider to restore Iphone in Itunes to be able to use it again. But normal restore failed and phone got into recovery mode. Keep getting following error message: "Iphone could not be restored. This device isn't eligible for the requested build".

Checked all software up-to-date. Tried to troubleshoot with test in Teminal, firewall off, identifying ports... Still getting same error message. Anybody successfully restored Iphone in similar situation? Any help much appreciated, thanks.