here is the console output during the agi call:
[2015-12-17 17:01:11] VERBOSE[6062][C-00000126] pbx.c: Executing [*1234@from-internal:4] AGI("SIP/2-00000181", "googletts.agi,"This is a simple google text to speech test in english.",en") in new stack
[2015-12-17 17:01:11] VERBOSE[6062][C-00000126] res_agi.c: Launched AGI Script /var/lib/asterisk/agi-bin/googletts.agi
[2015-12-17 17:01:12] VERBOSE[6062][C-00000126] res_agi.c: AGI Script googletts.agi completed, returning 0
[2015-12-17 17:01:12] VERBOSE[6062][C-00000126] pbx.c: Executing [*1234@from-internal:5] Hangup("SIP/2-00000181", "") in new stack
appreciate your help