This code system http://hl7.org/fhir/verificationresult-communication-method defines the following codes:

Code Display Definition
manual Manual The information is submitted/retrieved manually (e.g. by phone, fax, paper-based)
portal Portal The information is submitted/retrieved via a portal
pull Pull The information is retrieved (i.e. pulled) from a source (e.g. over an API)
push Push The information is sent (i.e. pushed) from a source (e.g. over an API, asynchronously, secure messaging)
<status value="active"/> <date value="2018-10-31"/> <publisher value="HL7 International"/> <contact> <telecom> <system value="other"/> <value value="http://hl7.org/fhir"/> </telecom> </contact> <description value="This code system defines the methods by which entities participating in a validation process share information (e.g. submission/retrieval of attested information, or exchange of validated information)."/> <caseSensitive value="true"/> <content value="complete"/> <concept> <code value="manual"/> <display value="Manual"/> <definition value="The information is submitted/retrieved manually (e.g. by phone, fax, paper-based)"/> </concept> <concept> <code value="portal"/> <display value="Portal"/> <definition value="The information is submitted/retrieved via a portal"/> </concept> <concept> <code value="pull"/> <display value="Pull"/> <definition value="The information is retrieved (i.e. pulled) from a source (e.g. over an API)"/> </concept> <concept> <code value="push"/> <display value="Push"/> <definition value="The information is sent (i.e. pushed) from a source (e.g. over an API, asynchronously, secure messaging)"/> </concept> </CodeSystem>