I'm curious what radio people are using with the STM32F4discovery? any near 900 MHz?
BTW, if anyone is interested in voice-over-*, there is the codec2 project coming out of the amateur-radio world that has the best voice compression rates for an open-source codec . codec2 is ported to the STM32F4 (requires the FPU). I know mesh isn't quite suited for reliable multi-hop streaming, but I believe it would be sufficient for delay-tolerant push-to-talk service.
I guess most of the STM32F4discovery-users are not strongly interested in radio communication. However, in general you can use any external transceiver that is based on SPI or I2C (and of course has RIOT support). Currently we *just* have the lowlevel support for the proprietary nrf24l01+ transceiver . I will do the adaptation to the ng_netdev interface according to the new network stack when this is in a stable state.
Also there are plans to add support for the external 802.15.4 transceiver MRF24J40MA. But I can't tell when this will be done.