Electronic – bridge from wireless mesh network to mobile device over bluetooth or wifi

My company builds devices that communicate over both cellular and wireless mesh networks. The devices gather data from industrial equipment and send that data over the Internet to our servers.

Currently our mesh network is homegrown. We're considering switching to another wireless mesh network: iDigi, Synapse, or an equivalent self-configuring mesh.

For data collection when no device in a location has good cell signal, we'd like to enable connectivity from mesh to smartphones carried by service technicians who periodically visit our devices. The idea is for the technician's phone to suck up un-sent data from the mesh and upload that data to the cloud when the phone next connects to the Internet. It's not financially practical to add bluetooth or wifi to our devices– we must use mesh for all non-cellular wireless connectivity.

All the mesh solutions we're considering use different radios than you'd find in a phone (no wifi-based mesh options met our requirements), so we need a bridge between the mesh and the phone.

Technicians' phones are either newer Android devices or older Windows Mobile 6.x device. We can't add cables or dongles to technicians' phones because they're too likley to be broken or dislodged– this means relying on the phone's existing bluetooth or wifi capabilities to communicate to the bridge.

So we need a mesh-to-phone bridge that:

• is rechargeable with a battery that lasts at least 12 hours.
• fits easily in a technician's pocket
• wirelessly communicates to the phone over wifi or bluetooth
• ideally is an off-the-shelf device we can buy or resell, although if we need to make a custom device one we can do so (as a last resort)
• ideally costs under $300 US

Got any suggestions for a good solution that meets these requirements, or at least comes close? Feel free to recommend a specific mesh implementation as well as a solution to by mesh-to-phone bridge problem.

The ideal solution would be a rechargeable mesh-to-bluetooth bridge, but I haven't found any of those from any mesh vendor.

The next-best option would be off-the-shelf components we could bundle together, like a mesh-to-serial bridge securely bolted to a serial-to-bluetooth bridge. Or a mesh-to-USB bridge combined with a USB-to-wifi bridge. And so on.

My next favorite option is to assemble a solution from 3rd-party modules on our own circuit board and case.

My least favorite option is to plug a serial cable into the device and a serial-to-bluetooth bridge like this one. This solution means lost tech time fiddling with (and breaking) cables so we'd like to avoid this if at all possible.

Got ideas?