With that 15 minute requirement, you are effectively imprisoning the employees at the office if they have a commute of more than 20 to 25 minutes.

@BartvanIngenSchenau: Presumably, the screen doesn't have to be in the office. These days, any screen with an Internet connection will do the trick in 95%+ of all cases.

@Hilmar, I was thinking more of a normal day in the office, directly followed by being on-call for the evening. You won't be able to be in front of a computer if you are still traveling to home and more than 15 min out from both home and office (or any other acceptable location to login from).

On-call response time normally means time to first response rather than time to solution. That first response may just be a query to the customer asking for more information, unless the task is something that can be done from a mobile terminal.

I was assuming a laptop at home would suffice. A 15 minute deadline means you pretty much cant leave your house. I wouldnt give up my day off for any amount of money let alone what these muppets are asking for - for free.

"If he genuinely asked and was informed "no on call" you can't force him to give up his personal time." - You can't force him even if he didn't ask. If the company didn't clearly present "on call" duties at the interview or in the contract, they don't exist, full stop.

"That first response may just be a query to the customer asking for more information, unless the task is something that can be done from a mobile terminal." - which should be made by a designated Support Team, not a software engineer. @keshlam

Every employment contract I've ever been offered has had a clause to the effect of "other duties as assigned". I'm not aware of this being particularly unusual for salaried software engineers, and I don't see how this doesn't cover a new "on call" rota, making the point in the first paragraph rather moot.

@RoddyoftheFrozenPeas it'd be rather unusual to treat "other duties" as "the duty to relinquish free time". I am not aware of this being a normal part of a job. And I don't think a judge would see it as a reasonable part of work, either. I feel like requiring 24 on-call presence on top of the already agreed upon work duties is more akin to exploitation as opposed to reasonable demand.

24-hour on-call means the risk of being woken up in the middle of the night — potentially multiple times per night, multiple nights running.  In addition to significant extra money, I'd also expect to get time off the following workday to make up for out-of-hours working.  Work laptops and mobile broadband would presumably ease some of the worst restrictions, but even then it's a serious imposition — one that you can't force people into against their will, nor without serious compensation.

I think "other duties as assigned" can likely cover on call or customer support duties, but not the additional number of hours, or the change in work hours.

Sorry if this comes across a little strongly worded Good on you for keeping it fairly mildly worded. I'm pretty sure my answer would have been a lot more strongly worded...

@RoddyoftheFrozenPeas, it's very unlikely that "other duties" would be held to cover latent 24/7 availability. Such "other duties" clauses are a way of enlarging the contractual job description, and the tasks which the worker can be put about during the working day, not enlarging the profile of working hours. And even if there was a clause that emphatically did have such broad scope, it risks judicial intervention, and being struck out of the contract as unreasonable or uncertain, or being modified (and curtailed) by implied terms.

I think the answer could be simplified even more. Tell the CTO that if they want 24 hour coverage then they hire (which means paying for) three-to-four times as many engineers, one group for each 8 hour shift throughout the week.

"I wouldnt give up my day off for any amount of money" If everybody is like you, the stack exchange sites will not survive. SE is 24/7 service. Imagine that the servers are down and no one is on duty, what will happen ? I can understand you will not sacrifice your personal time for business no matter how high is the pay. But, you must allow the business to pay a lot money to have staff on-call. Down-voting.

@Nobody If the business wants more coverage, they can hire more people. It's really not the employees' responsibility to cover for where the business lacks. That's promoting what I find to be a rather toxic mentality to make personal sacrifices for a company that is either inept or cheap. I really don't see any other option why the company would require the sacrifice on the part of employees to continue existing.

@VLAZ If the company pays high compensation for on-call, regardless new hire or not, why is it "sacrifice" ? You said "If the business wants more coverage, they can hire more people." If the present employees are willing to work on-call for high compensation, what's the point to hire new people ?

@Nobody if the people aren't willing to work 24 hours, then what's the point of faulting them for that?

@VLAZ I am only saying high compensation, if the employees don't accept the high pay, so be it. The manager can hire new employees to do it. The present employees will have to accept the consequences.

@Nobody that's not how your first comment reads. It definitely suggests that employees who are not willing to commit 24/7 to a job are at fault and you give example with the SE network potentially going down because such people aren't willing to be available outside their normal working hours. Yes, people might be willing but I'm not comfortable with the implication that it's wrong for people to opt not to.

"But, you must allow the business to pay a lot money to have staff on-call" is what I said. I downvoted this answer because we are talking on a 24/7 platform supported by on-call and the answerer says they don't want to sacrifice their personal time to do it. If every one is like that, we won't have this site. So, it's a morally wrong answer.

@VLAZ If you read this answer, you probably would understand what I mean. Academia.SE underwent a spam storm during the strike, a mod from another site used the emergency contact to notify SE, the on-call staff cleaned up the spams. If there were no on-call available, at least Academia.SE would be down for quite some time. Hope you understand better.

@Nobody "If every one is like that, we won't have this site." wrong. You seem to think the only way for a company to provide 24 hour support is for each employee to be reachable 24 hours at a time. No, you can have multiple shifts to cover the period, thus both the company has support around the clock and no single employee works more than their regular shift. Your suggestion that it's "morally wrong" for employees to not commit 24 hours is thus based on a misconception.