More than half of the mobile phone customers taking advantage of the ‘porting' service managed by the Telecommunications Carriers' Forum (TCF) are using it to jump to 2degrees, figures from the TCF have shown.

With April 1 representing the five-year anniversary of the introduction of ‘porting' – whereby a customer can switch their service provider but still keep the same phone number – the TCF has revealed that next month should also see the 500,000th port take place, based on the current rate.

Announcing its latest customer figures in February, 2degrees revealed that in total, 275,000 of their customers have ported their number from another network.

That figure followed an announcement in July that 200,000 customers had ported their numbers to 2degrees, meaning the network is making roughly 12,500 ports per month. TCF says around 13,000 ports currently take place per month overall.

TCF CEO David Stone couldn't be reached for comment, but says in a statement that reaching 500,000 ports is a ‘significant landmark' for the industry.

"At some point, we may see a levelling off in recorded porting activity as we reach a natural equilibrium with ported and non-ported numbers,” Stone says, "but for now, we have our eyes set on the one million mark, and at this rate that's not too far off.

The number porting service is estimated to have cost around $100 million to implement.