I'm a bit uncertain as to the question, but let's see if this helps any:
1) I assume you are talking about UserID in a Motorola trunked radio system (vs. MDC IDs in a conventional system).
2) For SmartNet/SmartZone radios, the UserID is programmed into the radio as a 4-digit hexadecimal number, in the range 0001h through FFFFh. For Astro 25 trunked systems (a/k/a 9600-baud systems), the User ID is programmed as a 9-digit decimal number in the range 1 - 9999999 (leading zeros not required).
3) If a subscriber radio is programmed for CallerID and the decoded ID does not correspond to an entry in an alias table, most SmartNet/SmartZone subscribers will translate the ID into a decimal number. The decimal equivalents of 0001h - FFFFh are 1 through 65,535. However, these subscriber radios add the decoded decimal value to 700000 in order to pad out the display. Thus, for instance, assume a given user's radio has the UserID of 000Ah. The decimal equivalent is 10. The decoded ID as displayed would be 700010.
4) To further complicate matters, some departments create SmartNet/SmartZone IDs by starting with some decimal value, padding it for some reason (such as to distinguish between a cruiser's fender number in the case of a mobile (MSP, for instance, adds 40,000) or an officer's badge number in the case of a take-home issued portable (MSP adds 50,000) -- and then the resulting decimal value is converted into a hex number for purposes of programming the radio.
For example:
Cruiser fender number = 1203.
Add 40,000 = 41203.
Convert to hex = A0F3h.
5) Working backwards with a decimal decoded SmartNet/SmartZone ID:
Example:
Decoded ID = 741203.
Substract 700,000 = 41203.
Convert to hex = A0F3. This is the UserID programmed in the radio.
Does this help?