SRV records (or service records) “tell” your domain name the exact location of the web server for any specified service. It is defined in RFC 2782 and has a 33 type code.
To set your SRV records in Microsoft Office 365, you need to log into cPanel and click on the Zone editor icon under the Domains section.

The Add a Record section lets you configure the new record. Here’s what you need to set:
Name | TTL | Type | Priority | Weight | Port | Target |
_sip._tls.domain_name. (for example, _sip._tls.freshcoffee.com.)
This value MUST end with a period (.) | 3600 | SRV | 100 | 1 | 443 | sipdir.online.lync.com. |
_sipfederationtls._tcp.domain_name. (for example, _sipfederationtls._tcp.freshcoffee.com.)
This value MUST end with a period (.) | 3600 | SRV | 100 | 1 | 5061 | sipfed.online.lync.com. |