Sistema Shyam TeleServices Ltd offers unlimited on-net calls to pre-paid users under a new tariff plan, ‘Always Talk’. The company, which provides telecom services under the ‘MTS’ brand, is offering unlimited calls under its new Rs 199 voucher. Calls made between users on the same network — in this case MTS to MTS — is termed as on-net calls. Additionally, customers will also get up to 1,000 minutes of free local calls on other networks, the company said in a release. The voucher comes with 30-day validity and is available across all its nine circles.