LOS ALTOS, CA – Smartphones continue to dial up big gains, but the overall cellphone market isn't generating much in the way of busy signals.

Global phone shipments were flat year-over-year for the first half, as a 40% jump in smartphone shipments was stifled by a 20% drop in dumbphone demand.

Overall smartphone shipments are expected to rise to 660 million this year, up 39.5% from 2011. Dumbphone shipments are forecast to fall 17.9%, however, for an aggregate drop of 2.7%, says Henderson Ventures.

The research firm chalks up the dismal results to economic factors that will be "partially relieved" next year, when deliveries are predicted to grow 6.2%, led by another 36% hike in smartphone shipments.

The overall communications industry is expected to grow 0.3% this year, but begin to accelerate through 2014, when it peaks at 9.1% growth. Currency appreciation of international currencies relative to the US dollar will make the growth seem even higher, Henderson said.