There were three stages done here.
The first was limiting the call completion costs. The big providers could set any price they wanted when other provider's subscribers were calling. This meant that the bigger the provider, the higher the cost they placed, causing small providers to be automatically more expensive than big ones.
The reform capped the call completion costs. Very soon after that providers started eliminating structured prices. The consumer pays the same amount, whether you call someone on the local operator, a different operator or a land line.
The second step was numbers migration. The government forced the cell operators to allow migrating customers to take their phone number with them. Over the past ten years I've changed operators at least 5 times, while still retaining the same cell phone number throughout.
The third step was to encourage small operators, and force the big ops to support MVNOs, and limit the pricing.
This step is actually a mixed bag in terms of how successful it was.The first small providers is called "Golan Telecom", offered a flat rate plan. You pay 100NIS per month, no matter how long you are on the phone. The plan also covers international calls and international roaming. You can spend as much as a month and a half out of every year abroad, and that is all you'll pay. That price was about a third of what all other operators would charge you at the time, and their plans had minutes limitations.
That was soon followed by other MVNO providers. Today I'm paying less than 30 NIS/month on my plan.
The reason I'm saying this was a mixed bag is that it did not, in fact, result in new operators popping up. Aside from Golan, who launched with a mix of their own network and MVNO, all other small providers were MVNO only.
And then Golan started rolling back its own network deployment. Today they are fully MVNO.
Still, with MVNOs having their own numbers, and the ability to migrate their entire network between the big providers, prices, so far, have not gone up for quite some time.
Another thing that happened, but I'm not sure whether that was government triggered or just a byproduct of everything else, is that operator locked phones are gone from the landscape.