Asterisk and FAX

Hello. I’d like to set up FAX service in Asterisk. What is better to use? I heard there is 2 options - the first one is use normal g711 codec and the second one is something like T.38. Where is a diffrent between that 2 codecs and how much it cost (gateways or somthhing)?. I need something what provide fax@email and email@fax with web GUI. What I can use?. Which option is better?. I have SIP/IAX termination - not interconnect to PSTN. Please for help. Thank’s. Bye