- Universal postal service quality convention, published on 20.9.2006
- Universal Postal Service Quality Convention (18.3.2004)
- Addendum to the Quality Convention for the Universal Postal Service approved between the Instituto das Comunicações de Portugal and the CTT - Correios de Portugal, S.A. (12.7.2002)
- Quality Convention of Universal Postal Service celebrated between the Instituto das Comunicações de Portugal and CTT - Correios de Portugal, S.A. (2001-2003)