SMS TPS Calculator
Calculate busy-hour SMS throughput (TPS) and SMSC capacity for 2G, 3G, LTE and 5G networks.
Technology
Total SIMs generating SMS traffic
Average including zero-users; typical 1–5
1.0 = one MT for each MO; >1 for bulk/A2P campaigns
Typically 8–15%
Active SMSC nodes handling traffic
Typical SMSC: 200–1000 TPS
SMSC Utilization
55.6 TPS per node / 600 TPS capacity
Daily MO volume
Mobile Originated SMS per day
Daily MT volume
Mobile Terminated SMS per day
MO SMS TPS (busy hour)
MO throughput during peak hour
MT SMS TPS (busy hour)
MT throughput during peak hour
Total SMS TPS
Combined MO + MT busy-hour throughput
Per SMSC TPS
Load distributed across 2 SMSC nodes
SMSC utilization
Per-node load vs. 600 TPS capacity
Protocol interface
Signaling path for 4G SMS delivery
SMS TPS Reference
SMSC dimensioning starts with estimating the busy-hour throughput in Transactions Per Second (TPS). Each MO or MT SMS counts as one transaction. The formulas below convert subscriber-level daily volumes into the peak-hour load that the SMSC must sustain.
Daily MO volume = Subscribers × MO SMS/sub/day
Busy-hour MO TPS = (Daily MO × BH%) / 3600
Busy-hour MT TPS = (Daily MT × BH%) / 3600
Total TPS = MO TPS + MT TPS
Per-SMSC TPS = Total TPS / SMSC count
| Generation | SMSC Interface | Protocol | NE involved |
|---|---|---|---|
| 2G (GSM) | MSC ↔ SMSC | MAP Send-RoutingInfo-for-SM / Forward-SM over SS7/SIGTRAN | MSC, HLR, SMS-GMSC, SMS-IWMSC |
| 3G (UMTS) | SGSN/MSC ↔ SMSC | MAP over SIGTRAN/IP | SGSN, MSC, HLR, SMS-IWMSC |
| 4G (LTE) | MME ↔ SMSC / MSC | SGd interface (Diameter Gdd/Sgd), SGs interface (MME–MSC) | MME, MSC, HSS, SMSC |
| 5G SA | AMF/SMF ↔ SMSF | N20 reference point (HTTP/2 SBI), Namf_Communication service | AMF, SMSF, UDM, SMF |
For the core signaling load from SMS procedures alongside other NAS procedures, combine with the signaling load calculator.
Frequently Asked Questions
What is SMS TPS and why does it matter for SMSC dimensioning?▾
TPS (Transactions Per Second) is the throughput metric used to dimension an SMSC (Short Message Service Centre). Each SMS submission (MO) and delivery (MT) counts as one transaction. During busy hour, the SMSC must process bursts of MO + MT messages; if TPS exceeds node capacity, messages queue up, delivery latency rises, and retries amplify the load. Operators typically dimension SMSC capacity with a 70–80% utilization ceiling.
What is the difference between MO SMS and MT SMS?▾
MO (Mobile Originated) SMS is sent by the subscriber from their device to the SMSC. MT (Mobile Terminated) SMS is delivered by the SMSC to the recipient's device. For person-to-person (P2P) traffic, every MO generates one MT, giving an MT/MO ratio of 1.0. Application-to-Person (A2P) traffic — such as OTP codes, marketing messages, and bulk alerts — can have an MT/MO ratio much greater than 1, since many MT messages are delivered for each MO submission.
How does SMS signaling differ between 2G/3G and 4G/5G?▾
In 2G/3G, SMS uses MAP (Mobile Application Part) over SS7/SIGTRAN — the MSC or SGSN relays messages between the UE and SMSC. In 4G, SMS-over-SGs uses the SGs interface (MSC–MME) to deliver SMS via the LTE NAS layer, while newer deployments use the SGd interface (MME–SMSC using Diameter). In 5G SA, the SMF forwards SMS via the N20 reference point using the HTTP/2 Service-Based Interface, and the AMF uses Namf_Communication for MT SMS notification.
What is a realistic busy hour factor for SMS?▾
Busy hour typically carries 8–15% of the daily SMS volume for consumer P2P traffic, concentrated in the evening peak (typically 7–9 PM local time). A2P/enterprise traffic has a flatter intraday pattern but can spike around marketing campaign launches. Using 10–12% as a planning input is conservative and recommended for capacity headroom.