The CTAPI Service Call Entry web service is modeled after the Solomon Screen: SD20000
The recommended and quickest way to implement is to use the ctDynamicsSL.fieldService.serviceDispatch.input.serviceCallEntry.screen object which contains all necessary objects to create SMServCall, SMServDetail and smServFault entries.

All necessary pv lookups are available in the service.
Examples:
public company[] getCompaniesByCpnyID(String cpnyID)
public ctDynamicsSL.SMContract[] getContractsForCustomerByContractID(String custID, String contractID)
public ctDynamicsSL.smCodeType[] getProblemsByCallTypeID(String callTypeID, String faultID)
public ctDynamicsSL.smSOAddress[] getSiteIDsByCustIDAndShipToID(String custID, String shipToID)
and more...

Contact Catalina for sample code for calling this webservice

Programmers Reference for: ctDynamicsSL.fieldService.serviceDispatch.input.serviceCallEntry