When I check the messages, all the newer calls are backed up because of an old message that I can't get off.

Your phone appears to be non-smart old phone
Sony Ericsson T250i User Manual
Your phone does not have SD card.
Your message (SMS or MMS) ought to be on the phone memory.
You can transfer the message to SIM if not already one.
Then read the sim on newer phone.
There can be a difficulty though as most new newer phones cannot take big or regular sized SIM
Alternatively Forward the message from old phone to newer Android phone wirelessly and then store using cloud or dropbox

You can access the answering system remotely by dialing your home telephone number from any touch-tone telephone. To remotely access the answering system
Dial your telephone number from any touch-tone telephone. When the answering system answers, enter the two-digit remote access code (19, unless you have changed it). The answering system automatically announces the number of messages (new or old) if there are any. If there are new messages, the answering system automatically begins to play new messages only. -OR If there are no new messages, the answering system automatically begins to play all old messages. You can also enter the remote commands: Play all messages
1 Press to listen to all messages. If there are new messages, the system plays back only the new messages (oldest first). If there are no new messages, the system plays back all old messages (oldest first). Play new messages
2 Press to listen to new messages only. Delete a message 3 Press during message playback to delete the current message. Delete all old messages
3 Press to delete all old messages. Replay current message or previous message
4 To repeat the message currently playing, press 4 after the answering system plays the day and time the current message was received. To listen to the previous message, press 4 while the answering system is playing the day and time the current message was received. Stop
5 Press to stop playback and recording. Play help menu * 5 Press to listen to a list of remote commands. Skip to next message
6 Press during playback to skip the current message and advance to the next message. Record a announcement
7 Press to record a new announcement. Begin speaking after the long beep. Turn system on or off 0 Press to turn the answering system on or off. Exit
8 or hang up Press to end remote access (the call is terminated). 1. 2. 3. 4.5
0 Answering system Remote access Hang up to end the call and save all messages.
NOTES: If you do not enter a valid remote access code, the system answers the call automatically. If the date and time is not set when a message is recorded, the system announces, "Time and date not set" before the answering system announces the number of messages. If there are no messages in the answering system, the system announces, "You have no message." If there are no new messages in the answering system, when you press 2 to play back new messages, the system announces, "You have no new message." If you pause for more than four seconds during remote access, you hear a help menu listing all features and commands. If there is no command for another 20 seconds, the call ends automatically. If the memory is full, the answering system answers after 10 rings and announces, "Memory is full. Enter the remote access code." Enter your remote access code to access the messages and announcements. When the answering system is turned off, the telephone answers after 10 rings and announces, "Please enter your remote access code."

Hello, I`ve tried to change the voice message on my phone and I hear the new message, when I play it back but if I call, the old message is still on. Also I`ve tried to desactivate the information and now the only message I hear is "Please leave a message" even though I still hear the old message true a call. Thanks for your input. This is a commercial phone so need to be reset asap!

Your cellphone provider should have provided you with certain data to set up your phone, depending on the phone type, the send and recieve settings for text messages and calls can vary.
If you did not recieve these your best option would be to call your cellphone provider helpdesk. Newer phones can be set-up by a simple text message from the provider. Or they might have to guide you trough the settings manually.

1.go to your message settings and check the message center number to see if it is correct
2. call to your network operator customer care
3. request the message center number...
4.note it down
5. go to message settings>message center number
6. insert the number which is noted by you and save it


this solves your messaging problem ...
Good luck

Try resetting the all the handsets by removing all the batteries for one minute. Then, put them back in and try it. This may reset the units. Also, check the batteries to make sure they are still good. You don't mention what kind of handset you have, but I think many of the different brands have built in voicemail. Are you sure you are not using the service voicemail instead of the handset voicemail?

These units are generally hardware modified to make them multizone. It may be that the newer discs use a slightly different zone coding and the modified hardware cannot handle this.

Settings:
In Settings dialog you can set the following options for Best Answering Machine:

* Greetings - allows setting up the greetings played on pick-up;
* Active in profiles - defines in which profiles the application will pick-up the phone and record messages;
* Storage - allows selecting on which disk the records will be saved;
* Pick up after - sets the time after which the call will be answered;
* Record time - maximum amount of time the message is being recorded;
* Format - message file format (amr,wav);
* Icon - configures the visibility of the icon displaying application activity and presence of new messages; depending on this parameter, can be shown in standby screen only (Phone application) or in any application;
* Play volume - play volume for the greeting;
* Records lifetime - automatically removes old messages;

Messages:
In this view you can listen to new and old messages, delete unnecessary messages, send the recorded messages and call the person directly from this view.

During the call:

When Answering Machine is processing an incoming call, you will see a dialog showing the application's progress with the ability to stop it:

* Answer - when this command is chosen during a call, it stops greeting playback or message record and you can continue talking to the caller;
* Hang up - stops greeting playback or message recording and terminates the call; hope this will be helpful...

STEP 1 : First check for the free space in the handset

1. selece the option icon in the main menu
2. scroll down and then select memory
3. check for the free space in the device.If the memory is full then delete some application.

After doing all the above steps with out switching off the handset remove the batery and sim after few seconds reinsert them again.
For refreshing the handset .


STEP 2:
Check the old messages are deleting are new one if old messages are deleting then follow the below steps.

1. Select the message icon from the main menu
2. Press menu button and select the Option
3. Select the general option
4. scroll down and select KEEP MESSAGES as per your wish (30days, 15 days, forverer)
5. After selecting any one of the option press menu button and select save .

if you select 15 or 30days the old messages will delete after 15 or 30 days.
If you select forever till you delete the messages it wont delete untill you delete them.

After doing all the above steps with out switching off the handset remove the batery and sim after few seconds reinsert them again.
For refreshing the handset

Step 3:
if the messages and call logs are deleting in between then there is problem in the handset software.You have to take the backup and then reinstall the software of the handset.

Probably not, but the voice mail extension is still a dialable number. Try 500 or 165 or asking whoever installed it what the extension is.

It will prompt you the same as if you had pressed the MESSAGE button, only there will not be any new messages. You just have to play the OLD messages and you'll hear them.


Carl