I never try to registered Cisco ATA but Audiocodes ones, see Thread 798-1031624.
These system are the same.
I first get the same result as you. The solution is in the ATA boxe. Here is a print of the ATA config i had. Hope you can find something same as Cisco ATA
H.323 Protocol Definition
General
* Connection Mode Normal
* Enable Annex D/T.38 FAX relay Yes
* Enable DTMF over H.245 No
H.323-ID : MP124_1
* Source Number Encoding Type E.164
* Destination Number Encoding Type E.164
* Q.931 Multiplexing No
Gatekeeper
Working with Gatekeeper Yes
GateKeeper IP Address 172.20.10.91
GateKeeper ID MoCS1000S
Gatekeeper Redundancy No
* Fallback to Internal Routing No
Gateway Registration Type H.323-ID
Register as Terminal No
Enable Mapping of Alias Number No
* Filter Calls To IP No
Enable RAI No
* RAI High Threshold 90
* RAI Low Threshold 90
RAI Loop Time 10
Gatekeeper Timers:
Registration Time [sec] 60
RAS Response Timeout [sec] 1
Number of RAS Retransmission 6
* Time Between GK Retries [sec] 60
* Coder Name (msec)
* 1st Coder g711Alaw64k 20
* 2nd Coder g729 30
* 3rd Coder
* 4th Coder
* 5th Coder
DTMF and Dialing Parameters
* Rx DTMF Option All
* 1st Tx DTMF Option RFC 2833
* 2nd Tx DTMF Option H.245 User Input
* 3rd Tx DTMF Option H.245 Signal Method
* 4th Tx DTMF Option Q.931 Info Message
* 5th Tx DTMF Option Not Supported
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* RFC 2833 Payload Type 96
* Hook Flash Option H.245 User Input
* Max Digits In Phone Number 24
* Interdigit Timeout [sec]: 2
* Digit Mapping Rules:
* Use '#','*' Digits for Dialing Yes
* Dial Tone Duration [sec] 16
Number Manipulation and Routing Modes
* Add Hunt Group Id as Prefix No
* Add Port Number as Prefix No
* IP To Tel Routing Mode Route calls before manipulation
* Tel To IP Routing Mode Route calls before manipulation
IP->Tel Remove Routing Table Prefix No
H.450 Supplementary Services
Enable Hold Yes
Enable Transfer Yes
Enable Call Waiting No
* Number of Call Waiting Indications 2
* Time Between Call Waiting Indications 10
Enable Call Forward Yes
Misc Parameters
* IP Security No
* Channel Select Mode By Phone Number
* Enable Busy Out No
* Enable Caller ID No
* Caller ID Type ETSI
* Polarity Reversal No
* Enable Current Disconnect No
* Enable DID Wink No
* Send DTMF over H225/Q.931 No
Release Call on "Setup Ack" No
* Does Setup Include Phone Number? Yes
* Default Destination Number 1000
* Number of Max Calls 24
H.323 Base Port 0
H.225 Listen Port 1720
H.225 Dial Port: 1720
* Enable Q931 Cause Yes
* Enable Alt Routing Tel2IP No
* Alt Routing Tel2IP Mode None
* CDR Report Level End Call