Simultaneous substitution or simsub, in Canadian broadcasting, is the practice by which cable, direct broadcast satellite and multichannel multipoint distribution service television distribution companies substitute a local Canadian signal over a non-Canadian or non-local signal, when two or more stations are airing the same programming at the same time.
Although sometimes controversial, this practice is required by the Canadian Radio-television and Telecommunications Commission as a way to protect the broadcast rights and commercial revenues of Canadian television broadcasters, by ensuring that the Canadian commercials are seen by nearly all viewers of the program.
For example, Global airs several hit American series such as The Simpsons. With simultaneous substitution, Global can ensure that advertisements purchased on their network are seen by nearly all Canadians watching the show at that particular time, rather than losing advertising revenue because some viewers were seeing the FOX affiliate's commercials instead. This issue is at its most controversial during the Super Bowl, where the simsub situation usually keeps Canadian audiences from seeing the American commercials that they would actually want to view during the Super Bowl. The replacement ads are often the same ones seen on Canadian television at all other times of the year, although the amount of "original" creative content by Canadian advertisers during recent editions has increased significantly.
Simultaneous substitutions are performed by the cable, satellite or MDS distributor, from a list submitted by the station in advance. Simultaneous substitution applies only to those methods of distribution. In principle, Terrestrial signals available in Canadian border markets are not, and cannot be, simsubbed. As well, simsubs can only be applied by cable companies in areas where the local station is available terrestrially.
Simsubs can only occur when a local and a non-local station are airing identical programming. Using the Simpsons example above, Global can only simsub a FOX affiliate airing the same episode of The Simpsons in the same time slot (hence "simultaneous"). The network cannot simsub if FOX is airing a different episode, and it cannot simsub a FOX affiliate airing the show at a different time.
However, one station, NTV in St. John's, has a reputation for being particularly sloppy about this; cable viewers frequently find NTV's programming, which can be as much as five minutes out of sync with respect to the American signals, substituted over signals that are sometimes not even carrying the same programming. (In fairness to the station, the substitution itself is performed by local cable operator Rogers Cable, although the station is responsible for requesting the substitutions.)
As well, some American stations whose signals are distributed in major Canadian cities (especially stations in rural northern Vermont which depend on carriage in Montreal for their financial viability, and to a lesser extent stations in Buffalo, New York, near Toronto) intentionally counterprogram against this rule, altering their schedules so that their programming is not simsubbed. This can set off so-called "chess games" between American television stations and the Canadian TV stations that air their Stateside counterparts' programming.
Although the market share and revenue provided by simultaneous substitution is a boom to the Canadian commercial broadcast television industry, the extent to which their schedules depend on matching American scheduling creates the unintended, and sometimes controversial, consequence of making it difficult to find viable timeslots in which to develop audiences for Canadian series.
