This is the destination phone number for the outbound call.
There are multiple ways to format phone numbers. They can include the 'tel:' prefix and/or the ANI and postd suffixes, e.g. ani=8009957586 and/or postd=2.
EX:
tel:+16175551234;ani=8009957586 (this sets the caller ID)
A masking number should be used for outbound calls calls as Fuse do not have a default caller ID value, and shows a destination for the person to respond and return the call.