WhatsApp seemed at first to be a lame idea: SMS, but carried over IP. I don’t care how my SMSs are carried, any more than I care how my supermarket refills it shelves.
But I now realise that it does many things better than SMSs.
To begin with, it’s reliable, compared to SMSs, which are lost too many times. And faster, reaching immediately, while SMSs can take some time. Carriers delivered a shoddy SMS service, and it’s no wonder that the market is now bypassing them. In fact, their modus operandi is not to provide a great service, but to take advantage of their customers.
WhatsApp is also more private than SMSs, which the Indian government can spy on. The carriers have to play by the government’s rules, and in any case, they don’t care for their customers’ privacy. And the Indian government has the Central Monitoring System, which gives them access to ALL call records, and probably all SMSs, without a court order. In fact, the government has access to carrier networks, which is a scary prospect. They can listen in without the carriers knowing who’s being monitored. The system was created without approval from Parliament, provides no means of redress in case of abuse, and places no consequences on the government in case of abuse.
Given all this sordid background, I feel more secure using WhatsApp. Facebook is a far better custodian of my data than the corrupt Indian carriers and government .
Then there’s money. WhatsApp is free, but if it were not, I’d happily give them a dollar a year. This is less than what Airtel charges, and even if it were the same, I’d much rather give my money to Facebook than to such a customer-hostile company as Airtel.
WhatsApp also doesn’t charge per SMS, so I tend to type multiple shorter messages, which together with WhatsApp’s much faster delivery, results in a live conversation like with IM apps.
When I travel outside India, I put in a local SIM card, so I miss SMSs sent to my India number. Or I may use the phone only on wifi, in which case I again miss SMSs. WhatsApp works in both cases.
WhatsApp doesn’t handle well the case where I’m traveling to the US, with a US SIM, and I call up a friend. After the call, if my friend wants to message me, he may logically send it to the number I called from. He may not know my primary, Indian number, and even if he does, he won’t send it there because he knows I’m in the US and using a US number. So he’d try to WhatsApp me on my US number, but it wouldn’t work, so he’d have to fall back to SMS. It’s a limitation of WhatsApp that we’ll have to use SMS despite both of us having WhatsApp.
iMessage handles this case better. It always stays in sync with your local number, so when you swap SIMs, your iMessage number changes immediately. So, the end result is that if you can SMS someone at a certain number, you can also iMessage them, and vice-versa, and it just works, without WhatsApp’s “which number should I message you on?” confusion.
The tradeoff is that iMessages sent to my Indian number don’t reach me any more. And, when I return to India, iMessages sent to my temporary US number no longer reach me, either.
Traveling is not the only situation in which people have multiple phone numbers. They may have a dual-SIM phone, or carry two phones.
WhatsApp and iMessage are both a step ahead of SMS, but only a step. We need another one, one that recognises that people have multiple numbers. For that matter, if someone has only my email ID, why shouldn’t she able to message me on WhatsApp?
Any unique identifier should be enough to contact someone. WhatsApp should allow you to verify and then claim multiple phone numbers and email IDs and a Facebook account  . And then, when someone wants to message you, it’s enough if they have just one of your identifiers.
And messaging any one of your identifiers should be same as messaging any other. iMessage messes this up. I don’t know whether to iMessage my cab mate on her email ID or phone number, because I don’t know which one she’s enabled for iMessage. I end up choosing wrong and having the message fail with a message saying that this phone number or email ID is not enabled for iMessage.
Chat apps need to recognise that all these identifiers are owned by the same person, so it doesn’t matter which one you use — the message should reach the recipient. Which is all that matters.
In conclusion, WhatsApp is a big step ahead of SMS. I wish someone takes the next step, supporting multiple phone numbers and email IDs and a Facebook account.
 My trust in Facebook is not absolute, but far more than than in the Indian set up.
 They’re owned by the same company after all.
 And ideally other unique IDs like Twitter, but given the politicalisation of APIs and companies randomly shutting down API access to their competitors, a company may not want to become dependent on another company.