Respondents to February's Unstrung poll say that a lack of interoperability among push-to-talk (PTT) services offered by separate carriers could be a big hurdle to the widespread adoption of these digital walkie-talkies.

PTT -- a technology, usually based on VOIP, that enables users to make quick calls to others on the network with the push of a button -- has been a hot topic in the cellular industry for the last couple of years. Carriers are hoping that adding the service for subscribers will reap the same kind of rewards it has for Nextel Communications Inc. (Nasdaq: NXTL). Smelling gold in them thar networks, all sorts of vendors -- from software and softswitch startups to major incumbents -- have been developing methods to adapt this technology for a full range of cellular networks.Initial offerings have started to emerge from startups like Kodiak Networks and Sonim Technologies Inc., and work is well underway at incumbents like LM Ericsson (Nasdaq: ERICY) and Nokia Corp. (NYSE: NOK).

Yet 52 percent of readers worry that a lack of interoperability could hold the growth of PTT back. There is standards work going on here, but -- as per usual -- it is very tricky to say when this will bear any fruit.

Otherwise, 58 percent of Unstrungers believe that despite the headstart that the startups have in developing these VOIP systems for GSM and CDMA networks, this market will eventually belong to the incumbent equipment vendors. There's proof of this happening already: Nextel supplier Motorola Inc. (NYSE: MOT) bought softswitch startup Winphoria last year; and Sonim has already developed strong ties with Ericsson in its bid to break into the European market.

And it is in Europe where 47 percent of you believe the next big market for PTT will evolve, now that the some of the major carriers in U.S. have started to offer such services. Early indications certainly show that European carriers are bullish about this technology -- for now

After all -- 40 percent of our readers reason -- the success of SMS in Europe has proven the demand for messaging services. Right?

Check out the full results from last month's poll here: PTT: Over and Out?. And while you're at it, why not take the opportunity to become just another number as part of March's poll on the much-hyped new HSDPA (High-Speed Downlink Packet Access) cellular technology: HSDPA: A Technology Too Far?.

— Dan Jones, Site Editor, Unstrung