Telecom mobile customers who have yet to make the switch to XT are unable to make or receive calls and texts from today when travelling in Australia and other countries that do not have CDMA networks. The company last night turned off its ''WorldMode'' service, which let owners of some more expensive CDMA mobiles roam overseas on networks based on alternative mobile technology GSM, using a Sim card. The dual-mode phones were introduced in 2006 as a stop-gap measure ahead of the launch of Telecom's XT mobile network in June last year. Telecom spokeswoman Emma-Kate Greer said all but 3 percent of customers who used their mobile overseas had switched to XT. Telecom had phoned and sent postcards to WorldMode customers to ensure they were not caught unawares, she said. ''In the past week, we have sent reminder messages to all customers currently roaming with the contact details for our roaming helpdesk for them to contact us. A further text message was sent [on Tuesday] to all roaming customers again to remind them of the cut off date.'' Telecom will axe its 3G CDMA mobile broadband service at the end of next month, meaning non-XT customers will notice a speed drop when using Telecom phones and datasticks to access the internet or download emails. It plans to close its CDMA network completely in 2012. 2degrees chief executive Eric Hertz has forecast the changes will create an opportunity for rival network operators to pick up customers, given that not all remaining CDMA customers may switch to XT.