Execute command before bringing interface up on OpenWRT

I'm making a Wireless-to-3g router with openwrt, and its working pretty well. To bring the 3g-wan interface up, I have to first register the USB modem using the command: gcom -d /dev/ttyUSB0 If I don't do this, chat will fail to establish connection with modem not registered errors. **My question**: Is there an option similar to pre-upon Debian to execute things before bringing an interface up, and only bring this up after successfully reaching this condition? Why? Because putting the gcom command on /etc/rc.local seems not to work, and it isn´t elegant. My current wan interface configuration: config interface 'wan' # === Conexão com a 3G da tim # option ifname ppp0 option ifname 3g-wan option username tim option password tim option pincode XXXX option proto 3g option service umts option device /dev/ttyUSB0 option dialnumber '*99***1#' option apn tim.br This solution must have an out-of-the-box experience because, after configured we deliver those boxes to users to create "remote offices" on distant places.