Hello Shaiban,
The number that appears on the caller ID will depend on your trunk settings (Menu > Digital and Telephony > Telephony > Trunks). From there you have a number of customization options, such as using that caller ID information associated with the queue that an agent is making an outbound call from, the information that is associated with the trunk, as well as a few other sources. You can even configure the priority of each of these so that the first caller ID information found will be used. You can read more about this in this Resource Center article.
Once you have purchased the DID number, You can assign it to a person, call flow, or phone.
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Jason Kleitz
Online Community Manager/Moderator
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