time delay and callback VP call

[carlosmouracorreia]

completes #371 and #372

[pep8speaks]

Hello @carlosmouracorreia! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file telephony/outcall_action.py:

Line 327:80: E501 line too long (142 > 79 characters)