MNP is implemented in different ways across the globe. The international and European standard is for a customer wishing to port his/her number to contact the new provider (Recipient) who will then arrange necessary process with the old provider . This is also known as 'Recipient-Led' porting. The UK is the only country to not implement a Recipient-Led system, where a customer wishing to port his/her number is required to contact the Donor to obtain a Porting Authorisation Code (PAC) which he/she then has to give to the Recipient. Once having received the PAC the Recipient continues the port process by contacting the Donor. This form of porting is also known as 'Donor-Led' and has been criticised by some industry analysts as being inefficient. It has also been observed that it may act as a customer deterrent as well as allowing the Donor an opportunity of 'winning-back' the customer. This might lead to distortion of competition, especially in the markets with new entrants that are yet to achieve scalability of operation.