The ISP I work for has a large block of IPs (randomly distributed) being blocked by AT&T so that mutual customers cannot log into online portals like att.net and directv.com. The common nodes of failure are cprodmasx.att.net and cprodx.att.com. We have had no luck getting through to higher tiers from customer-facing phone representatives, nor have we had a response when leaving a voicemail at 314-235-8168 (generic WHOIS registrant phone number, but recording mentions "domain administrator"; please check your voicemail and response; we just left another). Please have an AT&T server administrator reply off-list in regards to fixing this. Thank you