Since a few days we are facing an big issue with SPA 303 and 504G phones. when you restart the phone it will work for 30 minuts. then the phone will freeze. when you try to call the phone you get the message: temporary unavailable. the only solution is to restart the phone every 30 minuts.
we already did a reprovision of the phones so the phones have the latest firmware. we did also research in the network (sip ALG etc.). all this without luck. some of our clients are facing this issue to.