I have a macbook pro and have ichat i want to send iMessages but i can't.

Question

my sister has a brand new macbook air and she has the messages app but i have ichat and it does send anything to her even though i've added her as a buddy and it shows her contact number - my contacts are synced through iCloud and on ichat I'm using my yahoo as theres no option to use my iCloud. what do i do?

Answer 1

Hi,
iChat used to use Apple issued IDs  (@mac.com @me.com  @iCloud.com) as valid AIM screen Names due to an Agreement Apple have had with AOL for the last 14 years.
However at the end of June the older @mac.com and @me.com items stopped in iChat 5 and earlier due to changes for security reasons.
If you have Lion (OS X 10.7.x) which gives you the updated version of iChat 6 then you can still use these IDs.
Add the ID as if it is an AIM account using the password you use at Apple.
Your  sister will need to do the same (create a new AIM Account in Messages).  Most likely her computer is running mavericks (OS X 10.9.x)  and will only list AOL when trying to add an Account.
To be clear.
iChat can Login to the AIM service, Jabber servers and the Yahoo servers at iChat 6 plus it has the Bonjour account.
AIM names can be registered at AIM (AOL run a whole set of pages listed as "AIM").
AIM means AOL Instant Messenger.
AS I said above Apple Issued IDs are also valid as AIM Screen names and this continues in Messages in Mountain Lion and Mavericks.
Jabber servers can be Private (only those at the host site can join such as a company server) or Public. (anyone can join)
Google run a Jabber server based on Google Mail IDs
As you can see there is a separate Add option for this.
Facebook offer a chat option which gives you a Chat ID which is also Jabber based.
The Yahoo Option will only allow actual Yahoo IDs (despite several others being valid nowadays)
This service is text Only.
In both Apps the AIM connection must be to a valid AIM name (AIM to AIM)
Same for Jabber and Yahoo.
None of them will contact a Buddy on the other services. (AIM to Jabber does not work)
The iMessages account in the Messages app is another service like AIM and Jabber that Apple run which allows messaging to iOS devices as well as Macs.
But again it is a separate service and does iMessages to iMessages only, based on Apple IDs and iPhone numbers that have been registered with the service.
You may have worked out that an Apple Issued ID (@Mac.com, @me.com and @iCloud.com) can be the iMessages ID  AND the AIM valid Screen name
However your sister will need to enter the info twice - once in the iMessage Pane and again as an AIM/AOL add account option.
You may also have noticed that Jabber IDs look like emails.
Yahoo Account IDs are emails
AIM Account Names can be emails.
This does mean that you can add the "wrong" Buddy to the "Wrong" list and they will only appear as Off line as not check is done by any service on the validity of the name or ID being used.
There is one other thing you also need to know as you added an phone Number as Buddy.
This can actually be done on a AIM Buddy List  if the Phone is question is based in the United States and on one of these carriers.
Therefore you can Add a phone number if it has  a leading +1 as the Country Code.
Sticking in [phone] gets formatted like this in a Buddy list.
Try and use it and the AIM service will send this back to you.
9:48 pm      Wednesday; September 10, 2014
​  iMac 2.5Ghz i5 2011 (Mavericks 10.9)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
 Couple of iPhones and an iPad