It's the other way around in this case - "number" in the example refers to your number (the sender) and destination is the number which you are sending to (the receiving number). Technically these are SMPP addresses, but for sending SMS messages they are basically phone numbers. The sending number (*120*465#) doesn't look right to me - this should be the number of the sender.
1. You do need to check that the TON and NPI are correct:
The Type of Number (TON) indicates the scope of the address value, such as whether it is an international number (i.e. including the country code), a "national" or domestic number (i.e. without country code), and other formats such as "local" format (e.g. in the U.S., without an area code).
The NPI indicates the numbering plan used. The numbering plan chosen will aid the routing system in determining the correct network system to direct the message.
These will be provided by your provider.
2. You are using port 2775, which may well not be correct for your provider, try 1775 for a start, and verify it with your provider
3. Trying using the international form of the phone number, so instead of "083.." you would have "2783.." (drop the zero and add the country code for South Africa).