Make sure the call pickup group numbers does not overlap with the exiting dial plan
Call Pickup features include Pickup, GPickup, and OPickup:
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Pickup allows you to answer a call that is ringing on another phone within your “group” (a collection of extensions that your system administrator defines).
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GPickup allows you to answer a call ringing on a phone in another group.
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OPickup allows you to answer a call ringing on a phone in another group that is associated with your group
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how to call pickup from cisco spa900 sip phone from call manager 7.1