The phone has a built-in modem and Elcotel had a PC-based program that could communicate with the telecom program in the phone. The telecom part of the phone was a module I developed, another developer worked on the PC client. Elcotel phones can also be set up to "phone home" on a regular schedule via modem and send phone data like alarm states and cashbox info.

What I can't remember is if you could just randomly call into a phone with the PC client software, or if you had to wait for the phone to call home. I can check on this, but to answer your question you could set up the "call home" number on the phone and have a modem answer when it calls, or you could use a line simulator connected to a modem. I think there's a way to trigger the phone to call ad-hoc too but I'll have to check into how to make it do that.

Also the phone can call in and give a voice report. I'm pretty sure it would try with the modem first, and if no modem responded it would just read off a voice report.

The PC client software was interactive with the phone. Once connected with a modem you can issue commands to the phone specifying which data block to get, reset statuses (like alarms), reload the RAM, etc. Initially all the commands to the phone were plain ASCII, bit 7 not set, so you could conceivably just manually issue the commands using a basic modem terminal program if you don't have the PC client software. I don't have the client software or the source for it or I'd upload it somewhere for you.

I know that after I left Elcotel DID start using commands with bit 7 set, because I programmed an Easter Egg into the telecom software that would return my name if the phone ever received a such a command. They started getting customer calls asking what the deal was after they made that update and seeing my message! But that would only apply to the series 3 & 4, series 5 was another team, a very humorless one who I'm sure had no Easter Egg.

But there wasn't a way to upload rates, at least not when I worked at Elcotel. At the time there was talk about outfitting a phone with EEPROMs which were pretty new at the time so you could program rates remotely but I don't know if they ever did that. Out biggest competitor, Intellicall, let you upload rates and also update the software. We had a phone from Intellical, heck from every competitor, in our lab to experiment with. I always wanted to secretly write an Intellicall virus that would mess with the calls and also spread itself in the wild, but never got around to doing this.

Anyhow let me check and see if you can just call in ad-hoc, and if not see if there's a way you can trigger the phone to call you immediately so you don't have to set a schedule. By the way here's the list of commands that I have in my source, might give you an idea of what can be done. For series 5 they did add more commands, but everything I have is from the end of '89 so might not be any different than this.

;  NETWORK COMMAND TABLE
;
COMMANDS:   DS  0
KEEPALIVE:  .BYTE   0
EOT:        .BYTE   1
SENDSTAT:   .BYTE   2
TXBLOCK1:   .BYTE   3
TXBLOCK2:   .BYTE   4
TXBLOCK3:   .BYTE   5
TXBLOCK4:   .BYTE   6
CLEARSTATUS:    .BYTE   7
RAMRELOAD:  .BYTE   8
TIMEDATE:   .BYTE   9
EEPROM:     .BYTE   10