Designing Effective USSD Polling Campaigns: Best Practices

USSD Polling vs. SMS Surveys: Cost, Reach, and Response RatesMobile-based surveying remains one of the most practical ways to collect large-scale feedback in low‑ and middle‑income countries and in any context where smartphones or broadband are limited. Two widely used approaches are USSD (Unstructured Supplementary Service Data) polling and SMS (Short Message Service) surveys. Both have strengths and trade-offs across cost, geographic and demographic reach, response behavior, speed, and operational requirements. This article compares the two methods in depth and offers practical guidance for choosing between them and maximizing effectiveness.

What are USSD and SMS surveys?

USSD is a session-based protocol used mainly on feature phones and smartphones alike; respondents dial a short code (e.g., *123#) to initiate an interactive, menu-driven session where they respond by typing numbers/characters. USSD sessions are real-time and often used for mobile banking, airtime top-up, and interactive polls.
SMS surveys use text messages to send questions and receive replies. They can be one-way (broadcast a question and collect replies) or multi-turn (question–answer sequences keyed by the surveyor and respondent). SMS can be pushed (from a server) or pulled (user opts in and sends a keyword).

Cost

Direct costs

USSD: Typically more expensive per session than a single SMS because operators bill for session time or per interaction and because USSD requires a leased short code or gateway arrangement with mobile network operators (MNOs). Pricing varies widely by country and operator. Initial setup can include shortcode leasing, gateway integration, and compliance fees.
SMS: Generally cheaper per message in many markets, especially for outbound broadcast SMS. MMS or concatenated long messages cost more. Bulk SMS rates frequently drop as volume increases and can be very cost-effective for one-way messaging.

Indirect and operational costs

USSD requires integration with MNOs or third‑party aggregators and testing across operator networks — higher setup and operational overhead. However, USSD sessions are short and may reduce the need for follow‑ups.
SMS needs handling of varying reply formats, opt-outs, delivery receipts, and message concatenation; it also often requires more manual or automated follow-up to gather multi-question responses, increasing backend complexity.

Cost per complete response

Although USSD sessions cost more per interaction, their completion rate is often higher (see response rates below), which can reduce the effective cost per completed survey.
SMS can be cheaper per sent message but often requires multiple messages or reminders to get a complete response, raising the cost per usable result.

Reach

Device and network compatibility

USSD: Works on nearly all GSM phones without internet access—feature phones and smartphones alike—making it ideal for markets with low smartphone penetration. It functions over basic cellular signaling channels, so it generally works even with weak data coverage.
SMS: Also works on almost all phones, including feature phones. Delivery depends on SMS routing and store-and-forward systems; messages can be delayed if networks are congested.

Geographic and operator coverage

USSD implementations can be limited by operator agreements. Shortcodes and menus often require per-operator provisioning and may not be uniformly available across all carriers in a market without separate agreements.
SMS coverage is typically broader across operators because SMS routing is a core service; however, long codes and short codes may still require operator-level setup for high-volume campaigns or to enable two-way interactivity.

Language and localization

Both channels support localized languages, but USSD menus force shorter prompts and often numerically keyed responses (1, 2, 3), which simplifies localization. SMS allows longer text and richer phrasing, which can improve clarity but increases translation workload.

Response Rates and Quality

Typical response behaviors

USSD: Tends to produce high engagement and completion rates because sessions are immediate, interactive, and do not require the recipient to switch apps or wait for message delivery. Users select menu options quickly; the flow is guided, reducing partial or malformed answers.
SMS: Response rates vary widely. Broadcast SMS often gets low direct reply rates unless the recipient is already opted in or incentivized. SMS replies are free-form text, so answers can be incomplete, inconsistent, or require manual cleaning.

Speed of responses

USSD delivers real-time interactions and immediate responses; completion data is available instantly at session end.
SMS relies on store-and-forward; replies can be immediate but are often slower and subject to delays or delivery failures.

Data quality and structure

USSD’s constrained input (numeric options, short text) yields structured, easily analyzable data and fewer invalid responses.
SMS permits richer answers but increases the need for NLP or manual coding to standardize responses. Spam, typos, or off-topic replies are more frequent.

Incentives and user burden

USSD sessions are short and less burdensome, which improves completion even without incentives.
SMS may require incentives or multiple reminders to achieve similar completion volumes; each additional message increases campaign cost.

User Experience and Accessibility

USSD: Simple, menu-driven UX that is familiar in many markets. It avoids SMS costs for users in some operator arrangements and uses minimal cognitive load. However, USSD sessions can time out if the user is slow, and long multi-question flows become cumbersome.
SMS: Familiar for reading and later reference; messages persist in the inbox. Better for questions requiring detailed, free-text answers or when the user may want to draft a longer response. However, SMS threads can be fragmented, and users may ignore unknown numbers.

Technical and Compliance Considerations

Shortcodes/long codes: USSD needs a shortcode and operator provisioning; SMS can use shortcodes, long codes, Toll-Free Numbers, or aggregated routes — each with different cost and throughput implications.
Throughput: SMS gateways can scale to large broadcast volumes; USSD throughput can be constrained by operator session limits and concurrency allowances.
Opt-in & consent: SMS surveys typically require strict opt-in and clear consent for recurring messaging under many regulations. USSD, when initiated by the user (pull), implicitly contains user intent; push USSD (pushing a session to the user) is less common and more regulated.
Data privacy: Both channels transmit user responses via operator infrastructure; ensure storage and processing comply with relevant privacy laws (GDPR, local telecom regulations). For sensitive topics, prefer secure backends and minimal data retention.

When to choose USSD

You need high completion rates and structured answers in low‑bandwidth or feature‑phone-dominant markets.
Real-time, guided interactions are required (e.g., quick polls, mobile voting, immediate verification).
Respondents have limited literacy in written languages but can use numeric menu choices.
You want immediate availability of responses without a multi-message exchange.

Practical examples:

Agricultural extension services polling farmers about seed delivery timing.
Rapid public health symptom checks in remote regions.
Election pollsters seeking quick, structured feedback from a wide demographic.

When to choose SMS

You need to collect longer, free-text feedback or allow respondents to keep message copies.
The target population is already opted in or accustomed to interacting via SMS.
You need to send follow-ups, reminders, or multimedia links (via MMS or SMS with links).
Cost per message is a critical constraint and your campaign can tolerate lower completion or requires staged follow-ups.

Practical examples:

Customer support feedback where respondents describe experiences in their own words.
Marketing surveys sent to an existing subscriber base.
Situations where persistent records of messages are important for audit or follow-up.

Hybrid and complementary approaches

Combining USSD and SMS can capture the strengths of both:

Use SMS invites to advertise an opt-in USSD survey code (SMS → USSD pull). SMS informs; USSD collects structured answers.
Use USSD for quick structured data then send a follow-up SMS with a thank-you, link to deeper web survey, or confirmation receipt.
For low initial opt-in, run an SMS opt-in campaign that transitions respondents to USSD sessions for the actual survey.

Measuring cost-effectiveness: an example calculation

Let C_usd = cost per USSD session, R_usd = completion rate (fraction). Let C_sms = cost per SMS sent, N_sms = average number of messages needed per completed response, and R_sms = effective completion fraction per sequence.

Effective cost per completed response:

USSD: C_usd / R_usd
SMS: (C_sms * N_sms) / R_sms

Because USSD often has higher R_usd and lower N_sms (usually 1 session), its effective cost per completed, analyzable response can be competitive or superior despite a higher per-interaction price.

Practical tips to increase effectiveness

Keep flows short: Limit USSD to 4–6 steps and SMS to 160–320 characters per message where possible.
Use numerically keyed choices in USSD to simplify input and analysis.
Pretest across operators and devices to catch menu rendering, localization, and timing issues.
Localize language and phrasing; use simple, unambiguous wording.
For SMS, standardize reply formats with explicit instructions (e.g., “Reply 1 for Yes, 2 for No”) to encourage structured responses.
Monitor delivery rates and operator reports; adjust timings to avoid network congestion.
Respect local opt-in rules and include clear opt-out instructions for SMS.

Summary (concise)

Cost: SMS typically cheaper per message; USSD has higher per-session costs but often lower cost per completed response because of higher completion rates.
Reach: Both work on nearly all phones; USSD depends more on operator provisioning while SMS tends to have wider operator routing support.
Response rates: USSD usually yields higher completion and cleaner structured data; SMS gives lower, slower, and more free-form responses.

Choose USSD for short, high‑completion, structured surveys in feature‑phone or low‑connectivity contexts. Choose SMS when you need free-text responses, persistent message records, or are surveying an already opted-in subscriber base. Hybrid approaches often provide the best balance.