Pulse SMS does not currently have a way to compress GIFs. Many GIFs obtained from Gboard or other apps are larger than your carrier's size limit so they will not always get delivered. We recommend using Pulse SMS' internal Giphy search for GIFs because we are able to control the size of the animations that are downloaded. To access the GIF search feature, open a conversation, then tap the attach/paperclip icon. After that, tap the GIF icon and select the GIF you want to use.
In the future, we would like to be able to resize GIFs so that they can be searched and sent through any method.