Audiocodes MP118 8 FXO early media to Freeswitch SIP extension

I have one Audiocodes MP118 8FXO media gateway, between PSTN and internal SIP PBX Freeswitch, when calling from PSTN to IP, in this case, FXO automatic dialing ext 5001 on SIP server which is supposed to play IVR prompt, the problem is 1) many times when PSTN calls get answered some random media inserted before the right IVR prompt

2) some times the IVR prompt got cut off for the initial part

Audiocodes MP118 setup with not registering with SIP server, early media disabled. I have no single issue when calling from any SIP phones inside the network to the ext 5001 which is a main IVR.

could you please shed some light on this as you guys are Audiocodes experts?
Thanks,

Chris Chen