Adding a domain to Office 365 requires adding some DNS records.

The details are explained here Create DNS records at any DNS hosting provider for Office 365.

But, there are no clearly instruction to add SRV record with PowerAdmin.

Below you can find our setup for a example.com domain.

SRV records for Office 365 - _sip._tls

Name: _sip._tls
Type: SRV
Content: 1 443 sipdir.online.lync.com
Priority: 100
TTL: 3600

SRV records for Office 365 - _sipfederationtls._tcp

Name: _sipfederationtls._tcp
Type: SRV
Content: 1 5061 sipfed.online.lync.com
Priority: 100
TTL: 3600