For the last decade sms, telephone calls are extremely unreliable especially in India, as R&AW/CBI/NTRO are involved in large scale diversion and theft of smses and phone calls of harmless indian citizens especially link sellers, domain investors in the indian internet sector.
While this domain investor has faced the problem, in Moneylife magazine a report indicated that many people are not receiving the OTP sent by sms to their mobile phone in time when they are using internet bank or online transactions.
Registered postal mail, courier and speed post are the most reliable communication method, however it is time consuming and not very convenient, so a meeting is the easiest way to resolve issues for both business and personal matters