Another question that pop's up all the time is when doing call forwarding through the system how do you get the original calling party's caller ID to show up at the end destination? Let me rephrase just to make sure we are all on the same page. Let's say I forward a call to my mobile phone, I want to be able to see the original caller's phone number on my screen not my office's phone number.
Naturally, the question will be asked why I wouldn't just use the mobile ap for iOS, Android, Windows Mobile instead? The reality is those apps are good but when you are on the highway or in bad mobile data area's the app is not an option where making and receiving regular cell calls are instead.
What I suggest doing to accomplish this is to setup a 2nd trunk account in the phone system under "SIP Trunks" or "VoIP Providers". Many providers allow you to create as many username and password's or proxy accounts as you want while others do not. Make sure to check with your SIP provider before you go and make changes and then have to revert back because you didn't think this all the way through! Also, just like my last posting make sure your SIP provider allows for outbound caller ID overide or else this won't work!
Once you complete the steps below you can simply use a new outbound rule specifically when you forward to outside numbers from internal extensions to accomplish the desired effect!
Step 1: Log into the Management Console and go to VoIP Providers or SIP Trunks. Select the account in question and then go to the Outbound Parameters Tab.
Step 2: Scroll down to the From: Display Name and From: User Part fields and make sure the the setting for "OrigintorCallerID" are taken from the extension settings in the management console
Step 3: Don't forget about Apply and Ok (someone always forgets this part!)