The body has emphasised that the two-year review does not signal that the current regime is not functioning as well as it could.
Chief executive Alistair Buchanan said the system in use "has delivered much greater efficiency from the network operators with better quality of service, improved reliability and lower costs to consumers".
However, he added: "We need to know that the regime can continue to promote innovation from the companies at the level that is required for the future."
The review is the second investigation launched by the regulator in recent weeks.
It also recently announced that it was to also examine the electricity and gas supply markets amid concerns over a lack of competition in the area.
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