declare @obj int, @ret  int, @json varchar(max), @url varchar(max)
set @url = 'http://...'

exec @ret = sp_OACreate 'MSXML2.ServerXMLHTTP', @obj out
IF @ret <> 0 exec sp_OAGetErrorInfo @obj

exec @ret = sp_OAMethod @obj, 'Open', null, 'GET', @url, 'false'
if @ret <> 0 exec sp_OAGetErrorInfo @obj

exec @ret = sp_OAMethod @obj, 'setRequestHeader', null, 'Content-Type', 'text/xml; charset=utf-8'
if @ret <> 0 exec sp_OAGetErrorInfo @obj

exec @ret = sp_OAMethod @obj, 'setOption', null, 2 ,13056  -- игнорировать сертификат
if @ret <> 0 exec sp_OAGetErrorInfo @obj

EXEC @ret = sp_OAMethod @obj, 'SEND'
if @ret <> 0 exec sp_OAGetErrorInfo @obj
declare  @httpresult table (http varchar(max))

insert @httpresult EXEC @ret = sp_OAGetProperty @obj, 'responsetext'
IF @ret<>0 
EXEC sp_OAGetErrorInfo @obj

SELECT @json = http from @httpresult
select @json

EXEC @ret = sp_OADestroy @obj