Swedish cellcos Tele2 and Telia have announced that their 3G infrastructure joint venture Svenska UMTS-nat AB (SUNAB) is to begin phasing out its networks later this year with a view to shutting down its 3G services completely by 2025. Customers will be migrated from 3G to 4G networks, the firms say, as they look to cut costs and improve energy efficiency. SUNAB controls around 6,000 base transceiver stations (BTS) on behalf of its two owners and these will be reused for other technologies such as LTE or taken out of service.