# USSD features

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USSD allows for messages with a maximum of **182 characters**. However, due to differences in the minimum number of characters accepted by the Mobile Network Operators, we recommend you remain within **160 characters**.
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Clickatell offers two types of USSD messaging services: 

* **Mobile-initiated interactive messaging** **(or USSD pull):** This enables the customer to dial a number (e.g., \*100#) to initiate a session via their handset. Information could also be displayed as a menu that the customer can respond to and interact with.
* **Network-initiated interactive messaging** **(or USSD push):** This is when the session to the handset is initiated by the application. Similar to mobile-initiated, this information could be a menu that the customer can respond to and interact with.

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USSD push is not available in Chat Flow yet.
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These USSD messaging services are offered for all types of [service codes](https://guides.clickatell.com/ussd-user-guide/getting-started/service-codes).