March 20 (Reuters) - Canadian National Railway Co CNR.TO
* CN reaches tentative labour agreement with IBEW union representing signals and communications employees in Canada
* Says details of tentative agreement are being withheld pending ratification by union's membership
* Canadian National Railway Co - agreement to renew labour contract for approximately 700 CN signals and communications employees in Canada
* Says CN expects to hear results of IBEW's ratification vote in May
* Canadian National Railway Co says negotiated tentative agreement to renew labour contract for about 700 CN signals and communications employees Source text for Eikon: ID:nPnS8FxTa Further company coverage: CNR.TO