This problem is very interesting. dǎ 打in Chinese have a lot of meaning. for example： playing basketball dǎ lán qiú 打 篮 球 hit sb. dǎ rén 打 人 call him dǎ diàn huà 打电话 ask the news dǎ tīng 打 听 So, dǎ is a word for action. dǎ diàn huà 打电话means call someone or give sb. a call gěi can be a verb or a preposition. When gěi act as a preposition, it is equivalent to "to" in English. When gěi act as a verb, it is equivalent to "give" in English.

"dǎ"means"call", but the different is , it is just a verb in Chinese, "call" in English includes two words : verb+noun(call the phone/dǎ diànhuà) "gěi" means "to",it is a preposition.

This sentence can also translate into "I will give him a call" dǎ gěi means "give somebody a call"