Using web-service to send SMS from NAV

Recently I had a task to send SMS notification through the Webservice.
My service provider use following interface protocols.
Request for sending SMS:

Where:

• login and password are the authentication parameters;
• id is the internal message ID;
• recipient is the mobile phone number of the recipient;
• sender is a sender description;
• text is a message text.

This request should be posted to a webservice via HTTP or HTTPS.

The response has the following format:

Where 201 is the status code of the message sent.
Status code can be one of the following (only main codes are listed):

• 100 - message scheduled, delivery is not initiated yet;
• 102 - message delivered to destination;
• 2** - error codes: bad message format, recepient and so on.

I have created a special SMS Message table in NAV with the following structure:

I think there is no need to comment every field.
The trigger on inserting a record is following:

HTTP is 'Microsoft XML, v6.0'.XMLHTTP60 automation class. As you could see I realized special functions to save XML request and response for comfortable debugging in temporary windows directory. This lines could be wiped later.
When debugging that interface I was stuck by the fact, that ResponseXML returned zero-size document. This was happen because ContentType in ResponseHeader was text\html (not xml), therefore response could not be parsed by HTTP object. Obviously, I was forced to parse the response by loading document from the ResponseText (string variable).
To send SMS I used simple code below:

Webservice provide method to get delivery status of the posted messages.
Request:

Response:

I've created trigger on SMS Message table to update the status and initiate that trigger by the scheduler job: