Who do you use now? Retail and discount brokers usually use third parties so your broker needs an ECN (most commonly found in direct access brokers) to make AH trades...thinkorswim and interactive are two popular direct access brokers and should be able to perform AH trades. I'm sure someone else on here knows more than I do though
Edit: Apparently many online discounts offer ECN access as well:
Ameritrade (via Island ECN)
Hours: 8am-8pm Eastern; limit orders only during extended hours.
E*Trade (via Archipelago ECN)
Hours: 8am-8pm Eastern; limit orders only during extended hours. Note that eextended-hours orders can be placed even during regular market hours; these orders may be filled during normal or extended-trading hours.
Fidelity (via Redibook)
Hours: 7:30-915am and 4:15-8:00pm EST; restrictions on order types.
Harris Direct (via Redibook ECN)
Hours: 8-9:15am and 4:15-7pm Eastern; limit orders only; round lots.
Schwab (via Redibook ECN)
Hours: 7:30-9:15am and 4:15-8pm Eastern, Monday - Friday; limit orders only.
TD Waterhouse (via ???)
Hours: 7:30-9:30am and 4:15-7:00pm EST
http://www.invest-faq.com/articles/t...ter-hours.html