Start with making arrangements to have your phone answered and follow up with a reply call (basic courtesy). Otherwise don't be surprised when you show up with your grandiose project that you get told that:
1) you can't put it there because someone else did
answer their phone
2) you can't put it there because someone else followed through and had the space (tentatively assigned to you) assigned to them
3) you didn't bother to mention that your piece involved 400 gallons of gasoline and two tanks of hydrogen next to Kid's Camp because you didn't RESPOND TO THE PHONE CALLS.
Now answer the damn phone.