Required values to both retrieve existing sites, or register new ones...

Branch Code
Security Token
Caller Username
External Username
Language Code
SiteIdentifier
Branch Name
New Site (Y/N)
Return URL
Vendor Override Style
Portal Access(Y/V/N/_)
Options

Additional required fields to register new sites...

CustomerIdentifier
ContractIdentifier
ContractName
Route
Technician
Service name
Customer Salutation Type
Customer First Name
Customer Middle Name
Customer Last Name
Customer Title
Customer Address Line 1
Customer Address Line 2
Customer Address Line 3
Customer Address Line 4
Customer City
Customer State
Customer Zip
Customer Cell
Customer First Phone
Customer Second Phone
Customer Fax
Customer Webcustomer URL
Customer Email
Site Salutation Type
Site First Name
Site Middle Name
Site Last Name
Site Title
Site Address Line 1
Site Address Line 2
Site Address Line 3
Site Address Line 4
Site City
Site State
Site Zip
Site Cell
Site First Phone
Site Second Phone
Site Fax
Site Website URL
Site Email