PTA shall take measures to prevent restrictions which hinder undertakings in concluding agreements on interconnection. If PTA is of the opinion that interconnection may cause a danger of operational interference in the interconnected networks, it may issue instructions that the networks shall not be interconnected. PTA shall make public information on the obligations placed on electronic communications undertakings in accordance with this Chapter, together with information on the goods or service markets and geographical markets concerned. This information shall be accessible to all parties with interests at stake, provided it is not considered confidential. Agreements on interconnection and access must be sent to PTA immediately, or no later than one week after their signing. Article 25 Access to facilities PTA may oblige an electronic communications undertaking to negotiate agreements on co-location or other types of joint utilisation, including use of cable ducts or pipes, buildings or masts, as provided for in the second to fourth paragraphs. Where an electronic communications undertaking is entitled to set up or lay subterranean electronic communications facilities in common pasture land, public or private property, or to expropriate property, cf. Article 70, PTA shall encourage joint utilisation of the facilities or property, including co-location. If other electronic communications undertakings do not have access to comparable facilities due to environmental, health or security considerations, PTA may prescribe the joint utilisation of a facility or land. Such decisions shall only be taken following a public presentation and upon receiving opinions of interested parties. The PTA decision may involve instructions on sharing of cost of the facility or land. In special instances, involving special geographical locations or where envir-onmental considerations justify joint utilisation, PTA may issue instructions for such even if the provisions of the second paragraph do not apply. Article 26 Relations between electronic communications undertakings Electronic communications undertakings which acquire information from other undertakings in negotiating contracts for access or interconnection or after concluding contracts shall use the information solely for the purpose it was provided and shall maintain confidentiality at all times. The information may not be delivered to other parties, 14/34