Salaam Sister
No not all of them are, Alot of the donner meat is mixed with pork and all sorts even if the takeaway owners say it's Halal, Look for the one's that have HMC (Halal monitoring committee) stamped on it, Ask which ever takeaway you go to where they get their donner meat from and if its authenticated by HMC if they don't then I wouldn't trust it. I fancy some tonight might go and get some later yuum lolz!