Since the advent of telecommunication, SMS messaging has played an important role in communication. The usage of SMS messaging service has evolved over a period of time. Starting from personal messaging (P2P), SMS messaging service is widely used by enterprises for marketing (A2P) due to high reachability and ROI when compared to other communication channels.
The telecommunication which is initially designed for voice communication is enhanced for providing internet services to the subscribers. The quest for providing higher internet speeds has revolutionized the way network nodes operate and communicate with each other. The network nodes are enhanced to provide better internet speeds with low latency which has led to the evolution of multiple generations of telecom network which are referred as 2G, 3G, 4G, 5G etc. Despite the advancements in the telecom network generations, SMS messaging still remained as the key way of communication when compared to voice calls and other communication channels like email, OTT, App notifications etc.
SMSC is the network node which handles SMS messages in telecom network. In 2G/3G network, SMSC is integrated with MSC and SGSN via SIGTRAN protocol for receiving and sending SMS messages. The SMS messages will be sent as part of signaling messages where the size of the packet is limited. Hence only fixed number of characters can be sent in the SMS messages. In case of a big message, the SMS message will be split into multi-part and sent in multiple signaling messages.
3GPP has introduced 4G/LTE network which is capable of providing 10x the speeds of 3G network for mobile devices. Due to the higher data bandwidth availability in 4G network, VoLTE (Voice over LTE) is introduced where voice data packets will also be transmitted via internet channel. SMSC in 4G/LTE network can integrate with VoLTE network via SIP protocol for receiving and sending SMS messages. Unlike 2G/3G network, there is no need to split the SMS message into multi-part as there is no limitation on the number of characters that can be sent in the SMS message.
Operators who are upgrading their network from 2G/3G to 4G/LTE will have two options for enhancing their messaging network. The first option is to deploy an IPSMGW and integrate with their existing 2G/3G compatible SMSC. IPSMGW will act like a translator between VoLTE network and 2G/3G compatible SMSC by converting SIP traffic to SIGTRAN and vice versa. The second option is to enhance their existing SMSC to integrate with VoLTE network directly and handle SMS messages via SIP protocol. Telecom operators generally prefers the second option to avoid additional IPSMGW node in the network which becomes an overhead in latency, network capacity upgrade, OAM and performing SMS filtering.
High internet speeds and growth in smartphone usage in 4G/LTE era has resulted in the evolution of a new messaging channel known as OTT (Over The Top) applications like Whatsapp, Viber, Hike etc. Since these OTT applications communicate over internet, subscribers have the option of enjoying additional services along with messaging like sending images, videos, voice calls, video calls etc. This has resulted in significant reduction in P2P traffic in SMSCs. Due the adoption of different OTT applications in different parts of the world, enterprises still consider SMS as the primary channel of communication with subscribers. The raise in the number of enterprises and applications has resulted in a spike in A2P traffic in SMSCs and A2P messaging has become a key monetization factor for the telecom operators.
In order to leverage the high bandwidth availability in VoLTE network and to compete with the OTT applications, 3GPP has introduced a new channel of messaging called as RCS (Rich Communication Service) which is intended to replace traditional SMS service. RCS platform provides rich features like messaging, image transfer, video transfer, voice call, video call, group chat etc. which are available in OTT applications. RCS transfers all the messages through VoLTE network unlike OTT applications which transfer the messages through internet channel. The traditional SMS messaging client that is present in the handset will be replaced with the RCS client and all the RCS features will be provided to the subscriber by default which might help the telecom operators to regain their share in P2P traffic from OTT applications. Enterprises can also push rich content to the subscribers through RCS channel which helps in better ROI when compared to traditional text based SMS. Fallback to traditional SMS and MMS helps the enterprises to reach subscribers even though they are not available in VoLTE network.
Even though RCS looks promising, operators are still in a dilemma, regarding its adoption, considering the challenges that should be mitigated for launching RCS services effectively. The race for the monopoly in RCS has lead the handset and its OS vendors to limit the default SMS messaging client to connect to their respective RCS Core systems. This restrains the telecom operators to collaborate with the handset and its OS vendors for providing RCS services to their subscribers. Without the default SMS messaging client support, operator has to request the subscribers to download a RCS client application from application store to avail the RCS services which makes the penetration rate questionable. In a long run, after mitigating the challenges, RCS has the capability to take over OTT applications and emerge as a primary channel of messaging.