Verizon’s CFO Fran Shammo has flagged up potential quality-of-service concerns for smaller rivals T-Mobile US and Sprint following reports earlier this week they will provide MVNO capacity to Google.

Speaking with the Financial Times, Shammo suggested the additional traffic generated by the search giant’s service could be a worry.

“Google wants quality of service and there could be an issue if a bigger volume of traffic is placed on their networks,” he said.

The search giant wants to sell its own phone plans direct to consumers, probably starting later this year, according to a report this week.

Shammo’s comments followed Verizon’s fourth quarter results which showed the operator feeling its own pain, thanks to a fiercely competitive US cellular market.

Verizon Wireless gained two million retail postpaid connections in Q4 2014 but profitability took a tumble thanks to aggressive pricing and promotions.

The operator saw an 11 per cent increase in revenues in the period to $23.4 billion. Full-year revenue was $87.6 billion, up 8.2 percent compared with full-year 2013.

However, wireless operating margin fell by six percentage points to 23.5 per cent compared to Q4 2013. Verizon Wireless is feeling intensified competition from T-Mobile US and Sprint.

Overall, Verizon Wireless’ parent reported a loss of $2.23 billion for Q4 2014 compared with a profit of $5.07 billion a year earlier, although its performance was also impacted by pension payments. Revenue grew by 6.8 per cent to $33.2 billion.