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  <xs:element id="sncr_ZentryMember" abstract="true" name="ZentryMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sncr_CapitalStockSharesAuthorized" abstract="false" name="CapitalStockSharesAuthorized" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="sncr_CapitalStockParOrStatedValuePerShare" abstract="false" name="CapitalStockParOrStatedValuePerShare" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="sncr_NumberOfVotesEachShare" abstract="false" name="NumberOfVotesEachShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="sncr_NumberOfStockBasedCompensationPlans" abstract="false" name="NumberOfStockBasedCompensationPlans" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="sncr_DeferredCompensationShareBasedArrangementsLiabilityNonCurrent" abstract="false" name="DeferredCompensationShareBasedArrangementsLiabilityNonCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sncr_EmployeeAndDirectorsStockOptionsMember" abstract="false" name="EmployeeAndDirectorsStockOptionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sncr_ShareBasedPaymentArrangementAwardsClassifiedAsEquity" abstract="false" name="ShareBasedPaymentArrangementAwardsClassifiedAsEquity" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sncr_ShareBasedPaymentArrangementAwardsClassifiedAsLiability" abstract="false" name="ShareBasedPaymentArrangementAwardsClassifiedAsLiability" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sncr_IncomeTaxReceivableInterestIncome" abstract="false" name="IncomeTaxReceivableInterestIncome" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="sncr_OptionsAndUnvestedRestrictedSharesMember" abstract="true" name="OptionsAndUnvestedRestrictedSharesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="sncr_HanoverRateMember" abstract="true" name="HanoverRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
