The trade of natural gas takes place in line with that set out in the Natural Gas Sector Commercial Relations Regulation (RRCGN) and consists of the purchase, sale and resale of natural gas. Suppliers are entities holding natural gas supply licenses whose activity is conducted in a freely competitive environment, requiring registration in accordance with law. The Last Resort Supplier is considered to be one who is subject to public service requirements in the areas covered by the Public Natural Gas Network (RPGN). The activity of last resort supply is regulated by ERSE and is subject to licence requirement. Suppliers may acquire natural gas to supply their clients by establishing bilateral contracts or by participating in organized markets.
The commercial relationship between suppliers and the operators of infrastructures is established in infrastructure use contracts in accordance with the provisions of the Network and Infrastructures Access Regulations (RARII).