Embedded sip client

we need to develop something like this. more or less its a custom microphone acting as a sip client. just some explanation for now but can explain in detail, basically its a microphone connected to any single board computer(SBC), if possible we would like to develop this on the Arm ts7200/ts7400/ts7800. ill explain the unit first. its basically an embedded device. its used for recording clients voice and uploading it to a server and also act as a streaming client, since we are using asterisk server at the other end, i assume we need it to act as a sip client too if it is to communicate with asterisk. we are aware of pjsip and things like that as well, also embedded asterisk and such but dont have too much info about it or experience. so this unit, will have a microphone attached to [login to view URL] microphone is the source of the audio input. on top of this, it has lots of buttons, e.g we can program the buttons to like either be some selections, e.g call button, hangup button, some buttons with function and such, can explain later. it will have power on/off buttons, a volume meter (need this too as its important). we have some online stuff about volume meter leds/kits so maybe can integrate them or something. so some buttons,leds lights most of them have input functions and some of them if possible be taking a reading from the asterisk server, e.g if asterisk server is busy, there will be like a green light ON or something. the microphone as well if possible its using XLR connector, so maybe can have like a female/male port on the board and the microphone just connects to it that way, so in a sense its detachable. so just a rough explanation for now , the main idea is more or less to like develop a box with an sbc inside (this sbc will be connected via ip/network) and it has a console microphone attached to it for input and some buttons and such, similar to an ip phone but without the handset, just different led/keys and the microphone. anyway you can suggest as necessary, also feel free to suggest a budget if my estimations are too low. thanks.