5G: THE GREATEST SHOW ON EARTH!

Vol 53: Look up in the Sky! It's a Bird! It's a Plane! It's PCI 513 A benchmark study of T-Satellite, now with a suite of RCS Features

09/08/2025 | 42 pages
Price: $1,450.00

SRG just completed its 53rd 5G benchmark study. For this endeavor we collaborated with Accuver Americas and Rohde & Schwarz to conduct a benchmark study of the T-Mobile / Starlink T-Satellite service.  RCS features now include group chat, as well as support for picture and video attachments. We tested T-Satellite in the Rocky Mountain National Park with a second location at SRG HQ in Minnesota.

HIGHLIGHTS OF THE REPORT

Our Thanks.  We did this study with the support of Accuver Americas and Rohde & Schwarz.  Accuver provided us with its XCAL5 drive test software and XCAP post-processing software.  We used XCAL5 to control the RCS chats, including precise times when the messages were sent.  XCAL5 also monitored when the messages were received, as well as logged all the pertinent radio conditions and signaling information.  We used the TSMA scanner from R&S to independently monitor the T-Satellite radio conditions and the terrestrial networks when we were within coverage. Both companies have been trusted partners with us for nearly two decades.  SRG is responsible for all analysis and commentary provided in this report.

The Background.  Since testing the pre-commercial implementation of T-Satellite earlier this year, the functionality has expanded to include enhanced RCS features, such as group chats and the ability to include picture and video attachments.  The service also supports VZ and AT&T accounts, which have added T-Satellite functionality via an eSIM.

The Scope.  We tested one-to-one and one-to-many RCS sessions with up to 5 phones in the RCS group on both the non-terrestrial and terrestrial networks, including phones with AT&T and VZ physical SIMs.  These tests included both basic RCS text messages as well as RCS messages with a picture or video attachment.  Each test scenario included up to 30 messages to provide more reliable results.  We also included some tests with the iPhones, although the test scenarios were not as comprehensive due to the current limitations of the iPhone with RCS over T-Satellite.

The Analysis.  Beyond the basic message delivery times, we looked at T-Satellite availability based on RSRP and RRC connection activity – when are the phones attached, how frequently are they attached, and under what radio conditions.  RACH activity and Handover analysis was another key focus of the study.

The Results.  We observed meaningful improvements in the message delivery times with one-to-one messages, helped by reduced RACH activity.  The behavior of smartphones while using RCS also inherently helped, as we show in the report.  Delivery times with group chats and attachments could be quite good, but it wasn’t as consistent as it was with one-to-one chats.  iPhone functionality with RCS and T-Satellite has much room for improvement as does the handover success rate.

What Happens Next?  T-Satellite (T-Mobile and Starlink) will be introducing more demanding data-based services in the next several weeks.  It will be interesting to see how these services perform.