Integrate company mobile SIM cards into your VoIP system

Modern VoIP solutions offer fantastic mobility for your telephony because you can take your DID number and extension anywhere with an internet connection. However, many businesses and employees in Thailand still prefer to use mobile numbers.

This is largely because of the familiarity and habit of sharing mobile numbers and communicating by mobile phone, but there is also anecdotal evidence that people tend to ignore incoming landline number calls more than calls from a mobile number.

Whatever the reasons, a lot of Thailand-based businesses considering a VoIP solution ask how to integrate mobile SIM cards into their business telephony, instead of letting employees such as sales reps use their private mobile numbers for business purposes. Regrettably until now, this has been impossible as Thai law prevents mobile numbers to convert to internet protocol.

There is a now a practical workaround to this dilemma, in the form of a Closed User Group (CUG). In this CUG, mobile numbers are added to your group of DID numbers and extensions, and therefore become part of the same telephone eco-system….sort of!

So what are the benefits?

  • Within the Closed User Group (CUG), all calls are free of charge, which means your staff in the field can call their colleagues in the office (and vice versa) for as long as they like, and it doesn’t cost a cent…just as if they called from extension to extension.
  • Calls from customers to the office can easily be transferred to a CUG mobile number, or can be included in a Ring Group or assigned a Follow-me routing.
  • SIM cards and numbers are owned and assigned to employees by the company; if and when an employee leaves the company, customers calling their contact still call the company number instead of the employee who has moved on
  • All SIM card voice and data billing is neatly charged directly to the company instead of involving complex staff expenses claims.

Currently this solution still has some limitations:

  • Transfers from CUG mobiles to other CUG mobiles or extensions are not possible
  • Many standard VoIP features don’t apply to mobile SIM calls, for example call recordings, call history, voicemail to email, etc.…
  • SIM cards and voice & data service are provided and billed separately by a telco, at different rates to your VoIP internet calling rates.
  • The telcos offering these CUG SIM cards often require a minimum number of cards to be purchased, so it’s currently not an option for very small businesses.

However, for companies in Thailand who use or consider a VoIP solution, but who require the integration of mobile SIM numbers for their staff, the solution described here  works great and offers good business value… especially for companies with sales agents.

For more information, contact us on +66 2 105 4068 or email

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