Decentralized cellular networks where infrastructure ownership is distributed between several independent entities have emerged to increase overall network accessibility. In this setting, users can connect to any nearby, untrusted base station with no prior subscription to the operator. This talk will introduce Proof of Service as a method to address the primary challenges of ensuring reliable and trustworthy performance in this setting. Proof of Service redesigns the OCS to implement its escrow and charging functionalities separately using smart contracts and state channels respectively. An integral part of our design is the verification of delivered service to ensure that the user only pays commensurately. To do this, we introduce the notion of two-sided measurements where both the users and the providers independently assess the cellular service delivered. A key challenge is ensuring that these measurements reliably result in agreement. Our preliminary findings show that reconciling measurements from different layers of the cellular stack to arrive at a diverse set of matching observations is challenging but not impossible. Finally, this will be followed by a discussion of our ongoing implementation using Magma. This work is being done in collaboration with Witness Chain.