The blue chip mobile phone operator was up 3.5 per cent in early deals.
Elsewhere, consumer packaging firm Rexam rose 2.65 per cent, while insurer Admiral was up 2.55 per cent.
Completing the top five FTSE risers this morning was Associated British Foods – up two per cent in early trading – and Experian, which rose 1.9 per cent. This morning JP Morgan Cazenove upped its target price on shares in the financial information firm.
On the wider index, engineer Torotrak and transport firm FirstGroup rose 7.6 per cent and 7.5 per cent respectively.
Dragging on the blue chip index was a selection of weighty resources shares.
Russian steel producer Evraz was the biggest faller in early trades – shedding 2.3 per cent – as investors digested news of its £104m purchase of a majority stake in a Russian iron ore project.
Bank RBS was the biggest financial faller, off 1.5 per cent. Other banking shares fared slightly better: HSBC stock rose 0.5 per cent, Barclays was off 0.02 per cent and Lloyds Banking Group was flat.
Kazakh-focused miner Eurasian Natural Resources fell 1.3 per cent, while Chilean miner Antofagasta was off 1.1 per cent.
Pump maker Weir Group sank 1.1 per cent, while on the wider index miners Talvivaara and Kazakhmys also shouldered falls.
In Asia, the Nikkei closed down 1.08 per cent while in the US the Dow Jones closed down 0.04 per cent.