Electronic Circuit Design

We require a digital PCM bus interface capable of detecting single frequency audio tones, and, sending DTMF tones. The idea is that the PCM device makes a GSM type phone call (this is the master PCM/DVI device). The device you will create or have in your design library will allow us to detect tones on the RX audio channel, and send DTMF tones on the TX channel. Similar to a basic modem call something like this: RX 100mS 1400Hz TX DTMF TONES x 16 at 100mS on/off RX 750mS 2300Hz Notes: Currently we use a 16 bit uLaw PCM (DVI) bus from the Telit HE910 (could change to linear PCM if required). The design must be able to detect 1400Hz and 2300Hz audui tones down to 100mS precision. We must also be able to generate DTMF tones (send DTMF tones on the voice channel) down to 10mS i.e. 100mS on/off. The current PCM bus is programmed to run at 512Khz, 16 bit uLaw, 1 x TX channel, 1x RX channel is used. The circuit cost must be under USD$10 Design cost must be under USD$5000, if this is something you have in your design library then customising it for us should not be a problem. We can interface via UART ideally, or, I can write some flow charts / C Code into your DSP / Processor to talk back to my processor. We would require ownership for manufacturing / customizing purposes